Video region partition based on color format

ABSTRACT

A method of video processing is described. The method includes determining, for a conversion between a current video block of a video and a coded representation of the video, whether a certain partitioning scheme is allowed for the current video block according to a rule that depends on a coding mode type used for representing the current video block in the coded representation and a dimension of the current video block; and performing the conversion based on the determining.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2020/112975, filed on Sep. 2, 2020, which claims the priorityto and benefit of International Patent Application No.PCT/CN2019/103959, filed on Sep. 2, 2019. All the aforementioned patentapplications are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

This document is related to video and image coding and decodingtechnologies.

BACKGROUND

Digital video accounts for the largest bandwidth use on the internet andother digital communication networks. As the number of connected userdevices capable of receiving and displaying video increases, it isexpected that the bandwidth demand for digital video usage will continueto grow.

SUMMARY

The disclosed techniques may be used by video or image decoder orencoder embodiments for in which reference pictures are used in videocoding or decoding.

In one example aspect a method of video processing is disclosed. Themethod includes determining, for a conversion between a video region ofa video and a coded representation of the video, an intra codingcharacteristic of the video region based on a color format of the videoaccording to a rule; and performing the conversion according to theintra coding characteristic.

In another example aspect, another method of video processing isdisclosed. The method includes performing a conversion between a currentvideo block of a video and a coded representation of the video, whereinthe coded representation conforms to a format rule, and wherein theformat rule specifies a syntax element, modeType, indicative of a codingmode of the current video block, that is equal to eitherMODE_TYPE_NO_INTER that restricts use of the inter coding mode for theconversion, or MODE_TYPE_NO_INTRA that restricts use of the intra modefor the conversion.

In another example aspect, another method of video processing isdisclosed. The method includes performing a conversion between a videoand a coded representation of the video, wherein the codedrepresentation conforms to a format rule that specifies that a flagindicating a prediction mode constraint is not included in the codedrepresentation in case that a chroma format of the video is 4:2:2,4:0:0, or 4:4:4.

In another example aspect, another method of video processing isdisclosed. The method includes determining, for a conversion between avideo region of a video and a coded representation of the video, whetherand/or how a restriction on a size of a smallest chroma intra predictionblock to the video region is enabled according to a rule; and performingthe conversion based on the determining, wherein the rule is dependenton whether a color format of the video is 4:2:0 or 4:2:2.

In another example aspect, another method of video processing isdisclosed. The method includes determining, for a conversion between avideo region of a video and a coded representation of the video, whethera restriction on a size of a smallest chroma intra prediction block tothe video region is enabled according to a rule; and performing theconversion based on the determining, wherein the rule is dependent on acolor format of the video and/or a width (M) and a height (N) of thevideo region, and wherein the rule further specifies that, for the videoregion that is a coding tree node with a BT (binary tree) split, thenthe restriction on the smallest chroma intra prediction block isdisabled in case that 1) the color format of the video is 4:2:2 and 2)that a multiplication of M and N is a value from a set of values,wherein the set of values includes 64.

In another example aspect, another method of video processing isdisclosed. The method includes performing a conversion between a videoregion of a video and a coded representation of the video according to arestriction on a smallest chroma intra prediction block size, whereinthe coded representation conforms to a format rule that specifies avalue of a syntax field in the coded representation, due to a 4:2:2color format of the video.

In another example aspect, another method of video processing isdisclosed. The method includes determining, fora conversion between acurrent video block of a video and a coded representation of the video,an applicability of a partitioning scheme to the current video blockaccording to a rule; and performing the conversion based on thedetermining.

In another example aspect, another method of video processing isdisclosed. The method includes determining, for a conversion between avideo block of a video and a coded representation of the video, whetheran inter mode is enabled according to a rule, and performing theconversion based on the determining, wherein the rule specifies that theinter mode is enabled in case that a dual tree partitioning of lumasamples is enabled for the video block.

In another example aspect, another method of video processing isdisclosed. The method includes determining, for a conversion between avideo region of a video and a coded representation of the video, basedon a rule, whether use of a palette mode is permitted for the videoregion; and performing the conversion based on the determining, whereinthe palette mode includes encoding the video region using a palette ofrepresentative sample values.

In another example aspect, another method of video processing isdisclosed. The method includes performing a conversion between a currentvideo block of a video and a coded representation of the video, whereinthe coded representation conforms to a format rule, wherein the formatrule specifies a syntax element, modeType, that includes a MODE_TYPE_IBCthat allows use of an intra block copy mode for the conversion orMODE_TYPE_PALETTE that allows use of a palette mode for the conversion,wherein the intra block copy mode includes encoding the current videoblock using at least a block vector pointing to a video frame containingthe current video block, and wherein the palette mode includes encodingthe current video block using a palette of representative sample values.

In another example aspect, another method of video processing isdisclosed. The method includes determining, for a conversion between acurrent video block of a video and a coded representation of the video,whether a certain partitioning scheme is allowed for the current videoblock according to a rule that depends on a coding mode type used forrepresenting the current video block in the coded representation and adimension of the current video block; and performing the conversionbased on the determining.

In another example aspect, another method of video processing isdisclosed. The method includes performing a conversion between a videoblock of a video and a coded representation of the video, wherein thecoded representation conforms to a format rule, wherein the format rulespecifies that a characteristic of the video block controls whether asyntax element in the coded representation indicates a prediction modeof the video block.

In another example aspect, another method of video processing isdisclosed. The method includes performing a conversion between a videoregion of a first component of a video and a coded representation of thevideo, wherein the coded representation conforms to a format rule,wherein the format rule specifies whether and/or how a syntax field isconfigured in the coded representation to indicate a differentialquantization parameter for the video region depends on a splittingscheme used for splitting samples of the first component.

In another example aspect, another method of video processing isdisclosed. The method includes performing a conversion between a videoregion of a first component of a video and a coded representation of thevideo according to a rule, wherein the rule specifies, in case that adual tree and/or a local dual tree coding structure is applied to thevideo region, that a variable related to a differential quantizationparameter of the first component is not modified during a decoding orparsing process of a second component of the video.

In yet another example aspect, the above-described method may beimplemented by a video encoder apparatus that comprises a processor.

In yet another example aspect, the above-described method may beimplemented by a video decoder apparatus that comprises a processor.

In yet another example aspect, these methods may be embodied in the formof processor-executable instructions and stored on a computer-readableprogram medium.

These, and other, aspects are further described in the present document.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of intra block copy coding tool.

FIG. 2 shows an example of a block coded in palette mode.

FIG. 3 shows an example of use of palette predictor to signal paletteentries.

FIG. 4 shows an example of examples of Horizontal and vertical traversescans.

FIG. 5 shows examples of coding of palette indices.

FIG. 6 shows an example of 67 intra prediction modes.

FIG. 7 shows examples of the left and above neighbours of the currentblock.

FIG. 8 shows examples of ALF filter shapes (chroma: 5×5 diamond, luma:7×7 diamond).

FIG. 9 shows an example of sub sampled Laplacian calculation.

FIG. 10 shows an example of a modified block classification at virtualboundaries.

FIG. 11 is an example illustration of modified ALF filtering for Lumacomponent at virtual boundaries.

FIG. 12 shows examples of four 1-D 3-pixel patterns for the pixelclassification in EO.

FIG. 13 four bands are grouped together and represented by its startingband position.

FIG. 14 top and left neighboring blocks used in CIIP weight derivation.

FIG. 15 Luma mapping with chroma scaling architecture.

FIG. 16 shows examples of SCIPU.

FIG. 17 is a block diagram of an example of a hardware platform used forimplementing techniques described in the present document.

FIG. 18 is a flowchart for an example method of video processing.

FIG. 19 shows examples of positions of spatial merge candidates.

FIG. 20 shows examples of candidate pairs considered for redundancycheck of spatial merge candidates.

FIGS. 21A to 21G are flowcharts for example methods of video processing.

DETAILED DESCRIPTION

The present document provides various techniques that can be used by adecoder of image or video bitstreams to improve the quality ofdecompressed or decoded digital video or images. For brevity, the term“video” is used herein to include both a sequence of pictures(traditionally called video) and individual images. Furthermore, a videoencoder may also implement these techniques during the process ofencoding in order to reconstruct decoded frames used for furtherencoding.

Section headings are used in the present document for ease ofunderstanding and do not limit the embodiments and techniques to thecorresponding sections. As such, embodiments from one section can becombined with embodiments from other sections.

1. SUMMARY

This document is related to video coding technologies. Specifically, itis related to palette coding with employing base colors basedrepresentation in video coding. It may be applied to the existing videocoding standard like HEVC, or the standard (Versatile Video Coding) tobe finalized. It may be also applicable to future video coding standardsor video codec.

2. INITIAL DISCUSSION

Video coding standards have evolved primarily through the development ofthe well-known ITU-T and ISO/IEC standards. The ITU-T produced H.261 andH.263, ISO/IEC produced MPEG-1 and MPEG-4 Visual, and the twoorganizations jointly produced the H.262/MPEG-2 Video and H.264/MPEG-4Advanced Video Coding (AVC) and H.265/HEVC standards. Since H.262, thevideo coding standards are based on the hybrid video coding structurewherein temporal prediction plus transform coding are utilized. Toexplore the future video coding technologies beyond HEVC, Joint VideoExploration Team (JVET) was founded by VCEG and MPEG jointly in 2015.Since then, many new methods have been adopted by JVET and put into thereference software named Joint Exploration Model (JEM). In April 2018,the Joint Video Expert Team (JVET) between VCEG (Q6/16) and ISO/IEC JTC1SC29/WG11 (MPEG) was created to work on the VVC standard targeting at50% bitrate reduction compared to HEVC.

2.1 Intra Block Copy

Intra block copy (IBC), a.k.a. current picture referencing, has beenadopted in HEVC Screen Content Coding extensions (HEVC-SCC) and thecurrent VVC test model (VTM-4.0). IBC extends the concept of motioncompensation from inter-frame coding to intra-frame coding. Asdemonstrated in FIG. 1, the current block is predicted by a referenceblock in the same picture when IBC is applied. The samples in thereference block must have been already reconstructed before the currentblock is coded or decoded. Although IBC is not so efficient for mostcamera-captured sequences, it shows significant coding gains for screencontent. The reason is that there are lots of repeating patterns, suchas icons and text characters in a screen content picture. IBC can removethe redundancy between these repeating patterns effectively. InHEVC-SCC, an inter-coded coding unit (CU) can apply IBC if it choosesthe current picture as its reference picture. The MV is renamed as blockvector (BV) in this case, and a BV always has an integer-pixelprecision. To be compatible with main profile HEVC, the current pictureis marked as a “long-term” reference picture in the Decoded PictureBuffer (DPB). It should be noted that similarly, in multiple view/3Dvideo coding standards, the inter-view reference picture is also markedas a “long-term” reference picture.

Following a BV to find its reference block, the prediction can begenerated by copying the reference block. The residual can be got bysubtracting the reference pixels from the original signals. Thentransform and quantization can be applied as in other coding modes.

FIG. 1 is an illustration of Intra block copy.

However, when a reference block is outside of the picture, or overlapswith the current block, or outside of the reconstructed area, or outsideof the valid area restricted by some constrains, part or all pixelvalues are not defined. Basically, there are two solutions to handlesuch a problem. One is to disallow such a situation, e.g. in bitstreamconformance. The other is to apply padding for those undefined pixelvalues. The following sub-sessions describe the solutions in detail.

2.2 IBC in HEVC Screen Content Coding Extensions

In the screen content coding extensions of HEVC, when a block usescurrent picture as reference, it should guarantee that the wholereference block is within the available reconstructed area, as indicatedin the following spec text:

The variables offsetX and offsetY are derived as follows:

offsetX=(ChromaArrayType==0)?0:(mvCLX[0]&0x7?2:0)  (8-104)

offsetY=(ChromaArrayType==0)?0:(mvCLX[1]&0x7?2:0)  (8-105)

It is a requirement of bitstreams conformance that when the referencepicture is the current picture, the luma motion vector mvLX shall obeythe following constraints:

-   -   When the derivation process for z-scan order block availability        as specified in clause 6.4.1 is invoked with (xCurr, yCurr) set        equal to (xCb, yCb) and the neighbouring luma location (xNbY,        yNbY) set equal to (xPb+(mvLX[0]>>2)−offsetX,        yPb+(mvLX[1]>>2)−offsetY) as inputs, the output shall be equal        to TRUE.    -   When the derivation process for z-scan order block availability        as specified in clause 6.4.1 is invoked with (xCurr, yCurr) set        equal to (xCb, yCb) and the neighbouring luma location (xNbY,        yNbY) set equal to (xPb+(mvLX[0]>>2)+nPbW−1+offsetX,        yPb+(mvLX[1]>>2)+nPbH−1+offsetY) as inputs, the output shall be        equal to TRUE.    -   One or both of the following conditions shall be true:        -   The value of (mvLX[0]>>2)+nPbW+xB1+offsetX is less than or            equal to 0.        -   The value of (mvLX[1]>>2)+nPbH+yB1+offsetY is less than or            equal to 0.    -   The following condition shall be true:

(xPb+(mvLX[0]>>2)+nPbSw−1+offsetX)/CtbSizeY−xCb/CtbSizeY<=yCb/CtbSizeY−(yPb+(mvLX[1]>>2)+nPbSh−1+offsetY)/CtbSizeY  (8-106)

Thus, the case that the reference block overlaps with the current blockor the reference block is outside of the picture will not happen. Thereis no need to pad the reference or prediction block.

2.3 IBC in VVC Test Model

In the current VVC test model, i.e. VTM-4.0 design, the whole referenceblock should be with the current coding tree unit (CTU) and does notoverlap with the current block. Thus, there is no need to pad thereference or prediction block. The IBC flag is coded as a predictionmode of the current CU. Thus, there are totally three prediction modes,MODE_INTRA, MODE_INTER and MODE_IBC for each CU.

2.3.1 IBC Merge Mode

In IBC merge mode, an index pointing to an entry in the IBC mergecandidates list is parsed from the bitstream. The construction of theIBC merge list can be summarized according to the following sequence ofsteps:

Step 1: Derivation of spatial candidates

Step 2: Insertion of HMVP candidates

Step 3: Insertion of pairwise average candidates

In the derivation of spatial merge candidates, a maximum of four mergecandidates are selected among candidates located in the positionsdepicted in FIG. 19. The order of derivation is A₁, B₁, B₀, A₀ and B₂.Position B₂ is considered only when any PU of position A₁, B₁, B₀, A₀ isnot available (e.g. because it belongs to another slice or tile) or isnot coded with IBC mode. After candidate at position A₁ is added, theinsertion of the remaining candidates is subject to a redundancy checkwhich ensures that candidates with same motion information are excludedfrom the list so that coding efficiency is improved. To reducecomputational complexity, not all possible candidate pairs areconsidered in the mentioned redundancy check. Instead only the pairslinked with an arrow in FIG. 20 are considered and a candidate is onlyadded to the list if the corresponding candidate used for redundancycheck has not the same motion information.

After insertion of the spatial candidates, if the IBC merge list size isstill smaller than the maximum IBC merge list size, IBC candidates fromHMVP table may be inserted. Redundancy check are performed wheninserting the HMVP candidates.

Finally, pairwise average candidates are inserted into the IBC mergelist.

When a reference block identified by a merge candidate is outside of thepicture, or overlaps with the current block, or outside of thereconstructed area, or outside of the valid area restricted by someconstrains, the merge candidate is called invalid merge candidate.

It is noted that invalid merge candidates may be inserted into the IBCmerge list.

2.3.2 IBC AMVP Mode

In IBC AMVP mode, an AMVP index point to an entry in the IBC AMVP listis parsed from the bitstream. The construction of the IBC AMVP list canbe summarized according to the following sequence of steps:

Step 1: Derivation of spatial candidates

-   -   Check A₀, A₁ until an available candidate is found.    -   Check B₀, B₁, B₂ until an available candidate is found.

Step 2: Insertion of HMVP candidates

Step 3: Insertion of zero candidates

After insertion of the spatial candidates, if the IBC AMVP list size isstill smaller than the maximum IBC AMVP list size, IBC candidates fromHMVP table may be inserted.

Finally, zero candidates are inserted into the IBC AMVP list.

2.4 Palette Mode

The basic idea behind a palette mode is that the samples in the CU arerepresented by a small set of representative colour values. This set isreferred to as the palette. And it is also possible to indicate a samplethat is outside the palette by signalling an escape symbol followed by(possibly quantized) component values. This kind of sample is calledescape sample. The palette mode is illustrated in FIG. 2.

FIG. 2 shows an example of a block coded in palette mode.

2.5 Palette Mode in HEVC Screen Content Coding Extensions (HEVC-SCC)

In the palette mode in HEVC-SCC, a predictive way is used to code thepalette and index map.

2.5.1 Coding of the Palette Entries

For coding of the palette entries, a palette predictor is maintained.The maximum size of the palette as well as the palette predictor issignalled in the SPS. In HEVC-SCC, apalette_predictor_initializer_present_flag is introduced in the PPS.When this flag is 1, entries for initializing the palette predictor aresignalled in the bitstream. The palette predictor is initialized at thebeginning of each CTU row, each slice and each tile. Depending on thevalue of the palette_predictor_initializer_present_flag, the palettepredictor is reset to 0 or initialized using the palette predictorinitializer entries signalled in the PPS. In HEVC-SCC, a palettepredictor initializer of size 0 was enabled to allow explicit disablingof the palette predictor initialization at the PPS level.

For each entry in the palette predictor, a reuse flag is signalled toindicate whether it is part of the current palette. This is illustratedin FIG. 3. The reuse flags are sent using run-length coding of zeros.After this, the number of new palette entries are signalled usingexponential Golomb code of order 0. Finally, the component values forthe new palette entries are signalled.

FIG. 3 shows an example of use of palette predictor to signal paletteentries.

2.5.2 Coding of Palette Indices

The palette indices are coded using horizontal and vertical traversescans as shown in FIG. 4. The scan order is explicitly signalled in thebitstream using the palette_transpose_flag. For the rest of thesubsection it is assumed that the scan is horizontal.

FIG. 4 shows examples of Horizontal and vertical traverse scans.

The palette indices are coded using two main palette sample modes:‘INDEX’ and ‘COPY_ABOVE’. As explained previously, the escape symbol isalso signalled as an ‘INDEX’ mode and assigned an index equal to themaximum palette size. The mode is signalled using a flag except for thetop row or when the previous mode was ‘COPY_ABOVE’. In the ‘COPY_ABOVE’mode, the palette index of the sample in the row above is copied. In the‘INDEX’ mode, the palette index is explicitly signalled. For both‘INDEX’ and ‘COPY_ABOVE’ modes, a run value is signalled which specifiesthe number of subsequent samples that are also coded using the samemode. When escape symbol is part of the run in ‘INDEX’ or ‘COPY_ABOVE’mode, the escape component values are signalled for each escape symbol.The coding of palette indices is illustrated in FIG. 5.

This syntax order is accomplished as follows. First the number of indexvalues for the CU is signaled. This is followed by signaling of theactual index values for the entire CU using truncated binary coding.Both the number of indices as well as the index values are coded inbypass mode. This groups the index-related bypass bins together. Thenthe palette sample mode (if necessary) and run are signaled in aninterleaved manner. Finally, the component escape values correspondingto the escape samples for the entire CU are grouped together and codedin bypass mode.

An additional syntax element, last_run_type_flag, is signaled aftersignaling the index values. This syntax element, in conjunction with thenumber of indices, eliminates the need to signal the run valuecorresponding to the last run in the block.

In HEVC-SCC, the palette mode is also enabled for 4:2:2, 4:2:0, andmonochrome chroma formats. The signaling of the palette entries andpalette indices is almost identical for all the chroma formats. In caseof non-monochrome formats, each palette entry consists of 3 components.For the monochrome format, each palette entry consists of a singlecomponent. For sub sampled chroma directions, the chroma samples areassociated with luma sample indices that are divisible by 2. Afterreconstructing the palette indices for the CU, if a sample has only asingle component associated with it, only the first component of thepalette entry is used. The only difference in signaling is for theescape component values. For each escape sample, the number of escapecomponent values signaled may be different depending on the number ofcomponents associated with that sample.

In VVC, the dual tree coding structure is used on coding the intraslices, so the luma component and two chroma components may havedifferent palette and palette indices. In addition, the two chromacomponent shares same palette and palette indices.

FIG. 5 shows examples of coding of palette indices.

2.6 Intra Mode Coding in VVC

To capture the arbitrary edge directions presented in natural video, thenumber of directional intra modes in VTM5 is extended from 33, as usedin HEVC, to 65. The new directional modes not in HEVC are depicted asred dotted arrows in FIG. 6 and the planar and DC modes remain the same.These denser directional intra prediction modes apply for all blocksizes and for both luma and chroma intra predictions.

In VTM5, several conventional angular intra prediction modes areadaptively replaced with wide-angle intra prediction modes for thenon-square blocks.

In HEVC, every intra-coded block has a square shape and the length ofeach of its side is a power of 2. Thus, no division operations arerequired to generate an intra-predictor using DC mode. In VTM5, blockscan have a rectangular shape that necessitates the use of a divisionoperation per block in the general case. To avoid division operationsfor DC prediction, only the longer side is used to compute the averagefor non-square blocks.

FIG. 6 shows an example of 67 intra prediction modes.

To keep the complexity of the most probable mode (MPM) list generationlow, an intra mode coding method with 6 MPMs is used by considering twoavailable neighboring intra modes. The following three aspects areconsidered to construct the MPM list:

-   -   Default intra modes    -   Neighbouring intra modes    -   Derived intra modes

A unified 6-MPM list is used for intra blocks irrespective of whetherMRL and ISP coding tools are applied or not. The MPM list is constructedbased on intra modes of the left and above neighboring block. Supposethe mode of the left block is denoted as Left and the mode of the aboveblock is denoted as Above, the unified MPM list is constructed asfollows (The left and above blocks are shown in FIG. 7):

FIG. 7 is an example of the left and above neighbours of the currentblock.

When a neighboring block is not available, its intra mode is set toPlanar by default.

If both modes Left and Above are non-angular modes:

-   -   MPM list→{Planar, DC, V, H, V−4, V+4}

If one of modes Left and Above is angular mode, and the other isnon-angular:

-   -   Set a mode Max as the larger mode in Left and Above    -   MPM list→{Planar, Max, DC, Max−1, Max+1, Max−2}

If Left and Above are both angular and they are different:

-   -   Set a mode Max as the larger mode in Left and Above    -   if the difference of mode Left and Above is in the range of 2 to        62, inclusive        -   MPM list→{Planar, Left, Above, DC, Max−1, Max+1}    -   Otherwise        -   MPM list→{Planar, Left, Above, DC, Max−2, Max+2}

If Left and Above are both angular and they are the same:

-   -   MPM list→{Planar, Left, Left−1, Left+1, DC, Left−2}

Besides, the first bin of the mpm index codeword is CABAC context coded.In total three contexts are used, corresponding to whether the currentintra block is MRL enabled, ISP enabled, or a normal intra block.

During 6 MPM list generation process, pruning is used to removeduplicated modes so that only unique modes can be included into the MPMlist. For entropy coding of the 61 non-MPM modes, a Truncated BinaryCode (TBC) is used.

For chroma intra mode coding, a total of 8 intra modes are allowed forchroma intra mode coding. Those modes include five traditional intramodes and three cross-component linear model modes (CCLM, LM_A, andLM_L). Chroma mode signalling and derivation process are shown in Table2-. Chroma mode coding directly depends on the intra prediction mode ofthe corresponding luma block. Since separate block partitioningstructure for luma and chroma components is enabled in I slices, onechroma block may correspond to multiple luma blocks. Therefore, forChroma DM mode, the intra prediction mode of the corresponding lumablock covering the center position of the current chroma block isdirectly inherited.

TABLE 2-4 Derivation of chroma prediction mode from luma mode whencclm_is enabled Chroma Corresponding luma intra prediction modeprediction mode 0 50 18 1 X (0 <= X <= 66) 0 66 0 0 0 0 1 50 66 50 50 502 18 18 66 18 18 3 1 1 1 66 1 4 81 81 81 81 81 5 82 82 82 82 82 6 83 8383 83 83 7 0 50 18 1 X

2.7 Quantized Residual Block Differential Pulse-Code Modulation(QR-BDPCM)

In WET-M0413, a quantized residual block differential pulse-codemodulation (QR-BDPCM) is proposed to code screen contents efficiently.

The prediction directions used in QR-BDPCM can be vertical andhorizontal prediction modes. The intra prediction is done on the entireblock by sample copying in prediction direction (horizontal or verticalprediction) similar to intra prediction. The residual is quantized andthe delta between the quantized residual and its predictor (horizontalor vertical) quantized value is coded. This can be described by thefollowing: For a block of size M (rows)×N (cols), let r_(i,j), 0≤i≤M−1,0≤j≤N−1 be the prediction residual after performing intra predictionhorizontally (copying left neighbor pixel value across the predictedblock line by line) or vertically (copying top neighbor line to eachline in the predicted block) using unfiltered samples from above or leftblock boundary samples. Let Q(r_(i,j)), 0≤i≤M−1, 0≤j≤N−1 denote thequantized version of the residual r_(i,j), where residual is differencebetween original block and the predicted block values. Then the blockDPCM is applied to the quantized residual samples, resulting in modifiedM×N array {tilde over (R)} with elements {tilde over (r)}_(i,j). Whenvertical BDPCM is signalled:

$\begin{matrix}{{\overset{˜}{r}}_{i,j} = \left\{ \begin{matrix}{{Q\left( r_{i,j} \right)}\ ,} & {{i = 0},\ {0 \leq j \leq \left( {N - 1} \right)}} \\{{{Q\left( r_{i,j} \right)} - {Q\left( r_{{({i - 1})},j} \right)}}\ ,} & {{1 \leq i \leq \left( {M - 1} \right)}\ ,{0 \leq j \leq \left( {N - 1} \right)}}\end{matrix} \right.} & \left( {2\text{-}7\text{-}1} \right)\end{matrix}$

For horizontal prediction, similar rules apply, and the residualquantized samples are obtained by

$\begin{matrix}{{\overset{˜}{r}}_{ij} = \left\{ \begin{matrix}{{Q\left( r_{i,j} \right)}\ ,} & {{0 \leq i \leq \left( {M - 1} \right)},\ {j = 0}} \\{{{Q\left( r_{i,j} \right)} - {Q\left( r_{i,{({j - 1})}} \right)}},} & {{0 \leq i \leq {- \left( {M - 1} \right)}},{1 \leq j \leq \left( {N - 1} \right)}}\end{matrix} \right.} & \left( {2\text{-}7\text{-}2} \right)\end{matrix}$

The residual quantized samples {tilde over (r)}_(i,j) are sent to thedecoder.

On the decoder side, the above calculations are reversed to produceQ(r_(i,j)), 0≤i≤M−1, 0≤j≤N−1. For vertical prediction case,

Q(r _(i,j))=Σ_(k=0) ^(i) {tilde over (r)}_(k,j),0≤i≤(M−1),0≤j≤(N−1)  (2-7-3)

For horizontal case,

Q(r _(i,j))=Σ_(k=0) ^(j) {tilde over (r)}_(i,k),0≤i≤(M−1),0≤j≤(N−1)  (2-7-4)

The inverse quantized residuals, Q⁻¹(Q(r_(i,j))), are added to the intrablock prediction values to produce the reconstructed sample values.

The main benefit of this scheme is that the inverse DPCM can be done onthe fly during coefficient parsing simply adding the predictor as thecoefficients are parsed or it can be performed after parsing.

2.8 Adaptive Loop Filter

In the VTM5, an Adaptive Loop Filter (ALF) with block-based filteradaption is applied. For the luma component, one among 25 filters isselected for each 4×4 block, based on the direction and activity oflocal gradients.

2.8.1.1 Filter Shape

In the VTM5, two diamond filter shapes (as shown in FIG. 8) are used.The 7×7 diamond shape is applied for luma component and the 5×5 diamondshape is applied for chroma components.

FIG. 8 shows examples of ALF filter shapes (chroma: 5×5 diamond, luma:7×7 diamond)

2.8.1.2 Block Classification

For luma component, each 4×4 block is categorized into one out of 25classes. The classification index C is derived based on itsdirectionality D and a quantized value of activity Â, as follows:

C=5D+Â  (2-9-1)

To calculate D and Â, gradients of the horizontal, vertical and twodiagonal direction are first calculated using 1-D Laplacian:

g _(v)=Σ_(k=i-2) ^(i+3)Σ_(l=j-2) ^(j+3) V _(k,l) ,V_(k,l)=|2R(k,l)−R(k,l−1)−R(k,l+1)|  (2-9-2)

g _(h)=Σ_(k=i-2) ^(i+3)Σ_(l=j-2) ^(j+3) H _(k,l) ,H_(k,l)=|2R(k,l)−R(k−1,l)−R(k+1,l)|  (2-1)

g _(d1)=Σ_(k=i-2) ^(i+3)Σ_(l=j-3) ^(j+3) D1_(k,l),D1_(k,l)=|2R(k,l)−R(k−1,l−1)−R(k+1,l+1)|   (2-9-4)

g _(d2)=Σ_(k=i-2) ^(i+3)Σ_(j=j-2) ^(j+3) D2_(k,l),D2_(k,l)=|2R(k,l)−R(k−1,l+1)−R(k+1,l−1)|   (2-9-5)

Where indices i and j refer to the coordinates of the upper left samplewithin the 4×4 block and R(i,j) indicates a reconstructed sample atcoordinate (i,j).

To reduce the complexity of block classification, the subsampled 1-DLaplacian calculation is applied. As shown in FIG. 9 the same subsampled positions are used for gradient calculation of all directions.

FIG. 9 shows an example of sub sampled Laplacian calculation. (a) Subsampled positions for vertical gradient (b) Sub sampled positions forhorizontal gradient (c) Sub sampled positions for diagonal gradient (d)Sub sampled positions for diagonal gradient.

Then D maximum and minimum values of the gradients of horizontal andvertical directions are set as:

g _(h,v) ^(max)=max(g _(h) ,g _(v)),g _(h,v) ^(min)=min(g _(h) ,g_(v))  (2-9-6)

The maximum and minimum values of the gradient of two diagonaldirections are set as:

g _(d0,d1) ^(max)=max(g _(d0) ,g _(d1)),g _(d0,d1) ^(min)=min(g _(d0) ,g_(d1))  (2-9-7)

To derive the value of the directionality D, these values are comparedagainst each other and with two thresholds t₁ and t₂:

Step 1. If both g_(h,v) ^(max)≤t₁·g_(h,v) ^(min) and g_(d0,d1)^(max)≤t₁·g_(d0,d1) ^(min) are true, D is set to 0.Step 2. If g_(h,v) ^(max)/g_(h,v) ^(min)>g_(d0,d1) ^(max)/g_(d0,d1)^(min), continue from Step 3; otherwise continue from Step 4.Step 3. If g_(h,v) ^(max)>t₂·g_(h,v) ^(min), D is set to 2; otherwise Dis set to 1.Step 4. If g_(d0,d1) ^(max)>t₂·g_(d0,d1) ^(min), D is set to 4;otherwise D is set to 3.

The activity value A is calculated as:

A=Σ _(k=i-2) ^(i+3)Σ_(l=j-2) ^(j+3)(V _(k,l) +H _(k,l))  (2-9-8)

A is further quantized to the range of 0 to 4, inclusively, and thequantized value is denoted as Â.

For chroma components in a picture, no classification method is applied,i.e. a single set of ALF coefficients is applied for each chromacomponent.

2.8.1.3 Geometric Transformations of Filter Coefficients and ClippingValues

Before filtering each 4×4 luma block, geometric transformations such asrotation or diagonal and vertical flipping are applied to the filtercoefficients f(k,l) and to the corresponding filter clipping valuesc(k,l) depending on gradient values calculated for that block. This isequivalent to applying these transformations to the samples in thefilter support region. The idea is to make different blocks to which ALFis applied more similar by aligning their directionality.

Three geometric transformations, including diagonal, vertical flip androtation are introduced:

Diagonal:f _(D)(k,l)=f(l,k),c _(D)(k,l)=c(l,k),  (2-9-9)

Vertical flip:f _(V)(k,l)=f(k,K−l−1),c _(V)(k,l)=c(k,K−l−1)  (2-9-10)

Rotation:f _(R)(k,l)=f(K−l−1,k),c _(R)(k,l)=c(K−l−1,k)  (2-9-11)

where K is the size of the filter and 0≤k, l≤K−1 are coefficientscoordinates, such that location (0,0) is at the upper left corner andlocation (K−1, K−1) is at the lower right corner. The transformationsare applied to the filter coefficients f(k,l) and to the clipping valuesc(k,l) depending on gradient values calculated for that block. Therelationship between the transformation and the four gradients of thefour directions are summarized in the following table.

TABLE 2-5 Mapping of the gradient calculated for one block and thetransformations Gradient values Transformation g_(d2) < g_(d1) and g_(h)< g_(v) No transformation g_(d2) < g_(d1) and g_(v) < g_(h) Diagonalg_(d1) < g_(d2) and g_(h) < g_(v) Vertical flip g_(d1) < g_(d2) andg_(v) < g_(h) Rotation

2.8.1.4 Filter Parameters Signalling

In the VTM5, ALF filter parameters are signalled in Adaptation ParameterSet (APS). In one APS, up to 25 sets of luma filter coefficients andclipping value indexes, and up to one set of chroma filter coefficientsnd clipping value indexes could be signalled. To reduce bits overhead,filter coefficients of different classification can be merged. In sliceheader, the indices of the APSs used for the current slice are signaled.

Clipping value indexes, which are decoded from the APS, allowdetermining clipping values using a Luma table of clipping values and aChroma table of clipping values. These clipping values are dependent ofthe internal bitdepth. More precisely, the Luma table of clipping valuesand Chroma table of clipping values are obtained by the followingformulas:

$\begin{matrix}{{{AlfClip}_{L} = \left\{ {{{round}\mspace{11mu}\left( 2^{B\frac{N - n + 1}{N}} \right)\mspace{14mu}{for}\mspace{14mu} n} \in \left\lbrack {1..N} \right\rbrack} \right\}},} & \left( {2\text{-}9\text{-}13} \right) \\{{AlfClip}_{C} = \left\{ {{{round}\mspace{11mu}\left( {2^{{({B - 8})} + 8}\frac{\left( {N - n} \right)}{N - 1}} \right)\mspace{14mu}{for}\mspace{14mu} n} \in \left\lbrack {1..N} \right\rbrack} \right\}} & \left( {2\text{-}9\text{-}13} \right)\end{matrix}$

with B equal to the internal bitdepth and N equal to 4 which is thenumber of allowed clipping values in VTM5.0.

The filtering process can be controlled at CTB level. A flag is alwayssignalled to indicate whether ALF is applied to a luma CTB. A luma CTBcan choose a filter set among 16 fixed filter sets and the filter setsfrom APSs. A filter set index is signaled for a luma CTB to indicatewhich filter set is applied. The 16 fixed filter sets are pre-definedand hard-coded in both the encoder and the decoder.

The filter coefficients are quantized with norm equal to 128. In orderto restrict the multiplication complexity, a bitstream conformance isapplied so that the coefficient value of the non-central position shallbe in the range of −2⁷ to 2⁷−1, inclusive. The central positioncoefficient is not signalled in the bitstream and is considered as equalto 128.

2.8.1.5 Filtering Process

At decoder side, when ALF is enabled for a CTB, each sample R (i,j)within the CU is filtered, resulting in sample value R′(i,j) as shownbelow,

R′(i,j)=R(i,j)+((Σ_(k≠0)Σ_(l≠0)f(k,l)×K(R(i+k,j+l)−R(i,j),c(k,l))+64)>>7)  (2-9-14)

where f(k,l) denotes the decoded filter coefficients, K(x,y) is theclipping function and c(k,l) denotes the decoded clipping parameters.The variable k and l varies between

$- \frac{L}{2}$

and

$\frac{L}{2}$

where L denotes the filter length. The clipping functionK(x,y)=min(y,max(y,x)) which corresponds to the function Clip3(−y,y,x).

2.8.1.6 Virtual Boundary Filtering Process for Line Buffer Reduction

In VTM5, to reduce the line buffer requirement of ALF, modified blockclassification and filtering are employed for the samples nearhorizontal CTU boundaries. For this purpose, a virtual boundary isdefined as a line by shifting the horizontal CTU boundary with “N”samples as shown in FIG. 10 with N equal to 4 for the Luma component and2 for the Chroma component.

FIG. 10 shows an example of a modified block classification at virtualboundaries.

Modified block classification is applied for the Luma component asdepicted in FIG. 11 activity value A is accordingly scaled by takinginto account the reduced number of samples used in 1D Laplacian gradientcalculation.

For filtering processing, symmetric padding operation at the virtualboundaries are used for both Luma and Chroma components. As shown inFIG. 11, when the sample being filtered is located below the virtualboundary, the neighboring samples that are located above the virtualboundary are padded. Meanwhile, the corresponding samples at the othersides are also padded, symmetrically.

FIG. 11 shows examples of modified ALF filtering for Luma component atvirtual boundaries.

2.9 Sample Adaptive Offset (SAO)

Sample adaptive offset (SAO) is applied to the reconstructed signalafter the deblocking filter by using offsets specified for each CTB bythe encoder. The HM encoder first makes the decision on whether or notthe SAO process is to be applied for current slice. If SAO is appliedfor the slice, each CTB is classified as one of five SAO types as shownin Table 2-. The concept of SAO is to classify pixels into categoriesand reduces the distortion by adding an offset to pixels of eachcategory. SAO operation includes Edge Offset (EO) which uses edgeproperties for pixel classification in SAO type 1-4 and Band Offset (BO)which uses pixel intensity for pixel classification in SAO type 5. Eachapplicable CTB has SAO parameters including sao_merge_left_flag,sao_merge_up_flag, SAO type and four offsets. If sao_merge_left_flag isequal to 1, the current CTB will reuse the SAO type and offsets of theCTB to the left. If sao_merge_up_flag is equal to 1, the current CTBwill reuse SAO type and offsets of the CTB above.

TABLE 2-6 Specification of SAO type SAO sample adaptive offset Number oftype type to be used categories 0 None 0 1 1-D 0-degree pattern edgeoffset 4 2 1-D 90-degree pattern edge offset 4 3 1-D 135-degree patternedge offset 4 4 1-D 45-degree pattern edge offset 4 5 band offset 4

2.9.1 Operation of Each SAO Type

Edge offset uses four 1-D 3-pixel patterns for classification of thecurrent pixel p by consideration of edge directional information, asshown in FIG. 12. From left to right these are: 0-degree, 90-degree,135-degree and 45-degree.

FIG. 12 shows examples of four 1-D 3-pixel patterns for the pixelclassification in EO.

Each CTB is classified into one of five categories according to Table2-7.

TABLE 2-7 Pixel classification rule for EO Category Condition Meaning 0None of the below Largely monotonic 1 p < 2 neighbours Local minimum 2 p< 1 neighbour && Edge p == 1 neighbour 3 p >1 neighbour && Edge p == 1neighbour 4 p > 2 neighbours Local maximum

Band offset (BO) classifies all pixels in one CTB region into 32 uniformbands by using the five most significant bits of the pixel value as theband index. In other words, the pixel intensity range is divided into 32equal segments from zero to the maximum intensity value (e.g. 255 for8-bit pixels). Four adjacent bands are grouped together and each groupis indicated by its most left-hand position as shown in FIG. 13. Theencoder searches all position to get the group with the maximumdistortion reduction by compensating offset of each band.

FIG. 13 shows an example of four bands are grouped together andrepresented by its starting band position

2.10 Combined Inter and Intra Prediction (CIIP)

In VTM5, when a CU is coded in merge mode, if the CU contains at least64 luma samples (that is, CU width times CU height is equal to or largerthan 64), and if both CU width and CU height are less than 128 lumasamples, an additional flag is signalled to indicate if the combinedinter/intra prediction (CIIP) mode is applied to the current CU. As itsname indicates, the CIIP prediction combines an inter prediction signalwith an intra prediction signal. The inter prediction signal in the CIIPmode P_(inter) is derived using the same inter prediction processapplied to regular merge mode; and the intra prediction signal P_(intra)is derived following the regular intra prediction process with theplanar mode. Then, the intra and inter prediction signals are combinedusing weighted averaging, where the weight value is calculated dependingon the coding modes of the top and left neighbouring blocks (depicted inFIG. 14) as follows:

-   -   If the top neighbor is available and intra coded, then set        isIntraTop to 1, otherwise set isIntraTop to 0;    -   If the left neighbor is available and intra coded, then set        isIntraLeft to 1, otherwise set isIntraLeft to 0;    -   If (isIntraLeft+isIntraLeft) is equal to 2, then wt is set to 3;    -   Otherwise, if (isIntraLeft+isIntraLeft) is equal to 1, then wt        is set to 2;    -   Otherwise, set wt to 1.

The CIIP prediction is formed as follows:

P _(CIIP)=((4−wt)*P _(inter) +wt*P _(intra)+2)>>2  (3-2)

FIG. 14 shows examples of Top and left neighboring blocks used in CIIPweight derivation

2.11 Luma Mapping with Chroma Scaling (LMCS)

In VTM5, a coding tool called the luma mapping with chroma scaling(LMCS) is added as a new processing block before the loop filters. LMCShas two main components: 1) in-loop mapping of the luma component basedon adaptive piecewise linear models; 2) for the chroma components,luma-dependent chroma residual scaling is applied. FIG. 15 shows theLMCS architecture from decoder's perspective. The dotted blocks in FIG.15 indicate where the processing is applied in the mapped domain; andthese include the inverse quantization, inverse transform, luma intraprediction and adding of the luma prediction together with the lumaresidual. The unpatterned blocks in FIG. 15 indicate where theprocessing is applied in the original (i.e., non-mapped) domain; andthese include loop filters such as deblocking, ALF, and SAO, motioncompensated prediction, chroma intra prediction, adding of the chromaprediction together with the chroma residual, and storage of decodedpictures as reference pictures. The checkered blocks in FIG. 15 are thenew LMCS functional blocks, including forward and inverse mapping of theluma signal and a luma-dependent chroma scaling process. Like most othertools in VVC, LMCS can be enabled/disabled at the sequence level usingan SPS flag.

FIG. 15 shows examples of Luma mapping with chroma scaling architecture.

2.12 Dualtree Partitioning

In the current VVC design, for I slices, each CTU can be split intocoding units with 64×64 luma samples using an implicit quadtree splitand that these coding units are the root of two separate coding_treesyntax structure for luma and chroma.

Since the dual tree in intra picture allows to apply differentpartitioning in the chroma coding tree compared to the luma coding tree,the dual tree introduces longer coding pipeline and the QTBT MinQTSizeCvalue range and MinBtSizeY and MinTTSizeY in chroma tree allow smallchroma blocks such as 2×2, 4×2, and 2×4. It provides difficulties inpractical decoder design. Moreover, several prediction modes such asCCLM, planar and angular mode needs multiplication. In order toalleviate the above-mentioned issues, small chroma block sizes(2×2/2×4/4×2) are restricted in dual tree as a partitioning restriction.

2.13 Smallest Chroma Intra Prediction Unit (SCIPU) in JVET-O0050

Small chroma size is not friendly to hardware implementation. Indualtree cases, chroma blocks with too small sizes are disallowed.However, in singletree cases, VVC draft 5 still allows 2×2, 2×4, 4×2chroma blocks. To restrict the size of chroma block, in single codingtree, a SCIPU is defined in JVET-O0050 as a coding tree node whosechroma block size is larger than or equal to TH chroma samples and hasat least one child luma block smaller than 4TH luma samples, where TH isset to 16 in this contribution. It is required that in each SCIPU, allCBs are inter, or all CBs are non-inter, i.e, either intra or IBC. Incase of a non-inter SCIPU, it is further required that chroma of thenon-inter SCIPU shall not be further split and luma of the SCIPU isallowed to be further split. In this way, the smallest chroma intra CBsize is 16 chroma samples, and 2×2, 2×4, and 4×2 chroma CBs are removed.In addition, chroma scaling is not applied in case of a non-inter SCIPU.

Two SCIPU examples are shown in FIG. 16. In FIG. 16(a), one chroma CB of8×4 chroma samples and three luma CBs (4×8, 8×8, 4×8 luma CBs) form oneSCIPU because the ternary tree (TT) split from the 8×4 chroma sampleswould result in chroma CBs smaller than 16 chroma samples. In FIG.16(b), one chroma CB of 4×4 chroma samples (the left side of the 8×4chroma samples) and three luma CBs (8×4, 4×4, 4×4 luma CBs) form oneSCIPU, and the other one chroma CB of 4×4 samples (the right side of the8×4 chroma samples) and two luma CBs (8×4, 8×4 luma CBs) form one SCIPUbecause the binary tree (BT) split from the 4×4 chroma samples wouldresult in chroma CBs smaller than 16 chroma samples.

FIG. 16 shows SCIPU examples.

The type of a SCIPU is inferred to be non-inter if the current slice isan I-slice or the current SCIPU has a 4×4 luma partition in it afterfurther split one time (because no inter 4×4 is allowed in VVC);otherwise, the type of the SCIPU (inter or non-inter) is indicated byone signalled flag before parsing the CUs in the SCIPU.

2.14 Small Chroma Block Constrains in VVC Draft 6

In VVC draft 6 (JVET-O2001-vE.docx), the constrains on small chromablocks are implemented as follows (related part is marked in

).

Descriptor coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, qgOnC,cbSubdiv, cqtDepth, mttDepth, depthOffset,     partIdx,  

 

 ) {  ...  if( split_cu_flag ) {   if( ( allowSplitBtVer | |allowSplitBtHor | | allowSplitTtVer | | allowSplitTtHor) &&   allowSplitQT )   split_qt_flag ae (v)  if( !split_qt_flag ) {   if( (allowSplitBtHor | | allowSplitTtHor ) &&     ( allowSplitBtVer | |allowSplitTtVer ) )    mtt_split_cu_vertical_flag ae (v)   if( (allowSplitBtVer && allowSplitTtVer && mtt_split_cu_vertical_flag) | |   ( allowSplitBtHor && allowSplitTtHor && !mtt_split_cu_vertical_flag ))    mtt_split_cu_binary_flag ae (v)   }   

 

  

 

  

 

  

ae (v)   

 

 

 

  

  

  

  

 

 

  if( !split_qt_flag ) {   if( MttSplitMode[ x0 ][ y0 ][ mttDepth ] = =SPLIT_BT_VER ) {    depthOffset += ( x0 + cbWidth >pic_width_in_luma_samples ) ? 1 : 0    x1 = x0 + ( cbWidth / 2 )   coding_tree( x0, y0, cbWidth/ 2, cbHeight, qgOnY, qgOnC, cbSubdiv +1,       cqtDepth, mttDepth + 1, depthOffset, 0, treeType, modeType )   if( x1 < pic_width_in_luma_samples)     coding_tree( x1, y0, cbWidth/ 2, cbHeightY, qgOnY, qgOnC, cbSubdiv + 1,       cqtDepth, mttDepth +1, depthOffset, 1, treeType, modeType )   } else if( MttSplitMode[ x0 ][y0 ][ mttDepth ] = = SPLIT_BT_HOR ) {    depthOffset += (y0 +cbHeight > pic_height_in_luma_samples ) ? 1 : 0    y1 = y0 + ( cbHeight/ 2 )    coding_tree( x0, y0, cbWidth, cbHeight / 2, qgOnY, qgOnC,cbSubdiv + 1,      cqtDepth, mttDepth + 1, depthOffset, 0, treeType,modeType )    if( y1 <pic height in luma samples)     coding_tree( x0,y1, cbWidth, cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 1,       cqtDepth,mttDepth + 1, depthOffset, 1, treeType, modeType )   } else if(MttSplitMode[ x0 ][ y0 ][ mttDepth ] = = SPLIT_TT_VER ){    x1 = x0 + (cbWidth / 4 )    x2 = x0 + ( 3 * cbWidth / 4 )    qgOnY = qgOnY && (cbSubdiv + 2 <= cu_qp_delta_subdiv )    qgOnC = qgOnC && ( cbSubdiv + 2<= cu_chroma_qp_offset_subdiv )    coding_tree( x0, y0, cbWidth/4,cbHeight, qgOnY, qgOnC, cbSubdiv + 2,      cqtDepth, mttDepth + 1,depthOffset, 0, treeType, modeType )    coding_tree( x1, y0, cbWidth/2,cbHeight, qgOnY, qgOnC, cbSubdiv + 1,      cqtDepth, mttDepth + 1,depthOffset, 1, treeType, modeType )    coding_tree( x2, y0, cbWidth/4,cbHeight, qgOnY, qgOnC, cbSubdiv + 2,      cqtDepth, mttDepth + 1,depthOffset, 2, treeType, modeType )   } else {/* SPLIT_TT_HOR */    y1= y0 + ( cbHeight / 4 )    y2 = y0 + ( 3 * cbHeight/ 4 )    qgOnY =qgOnY && ( cbSubdiv + 2 <= cu_qp_delta_subdiv )    qgOnC = qgOnC && (cbSubdiv + 2 <= cu_chroma qp_offset_subdiv )    coding_tree( x0, y0,cbWidth, cbHeight / 4, qgOnY, qgOnC, cbSubdiv + 2,     cqtDepth,mttDepth + 1, depthOffset, 0, treeType, modeType )    coding_tree( x0,y1, cbWidth, cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 1,     cqtDepth,mttDepth + 1, depthOffset, 1, treeType, modeType )    coding_tree( x0,y2, cbWidth, cbHeight / 4, qgOnY, qgOnC, cbSubdiv + 2,     cqtDepth,mttDepth + 1, depthOffset, 2, treeType, modeType )   }   } else {   x1 =x0 + ( cbWidth / 2 )   y1 = y0 + ( cbHeight/ 2 )   coding_tree( x0, y0,cbWidth / 2, cbHeight / 2, qgOnY, qgOnC, cbSubdiv +2,     cqtDepth + 1,0, 0, 0, treeType, modeType )   if( x1 < pic_width_in_luma_samples )   coding_tree( x1, y0, cbWidth / 2, cbHeight / 2, qgOnY, qgOnC,cbSubdiv + 2,     cqtDepth + 1, 0, 0, 1, treeType, modeType )   if( y1 <pic_height_in_luma_samples )    coding_tree( x0, y1, cbWidth / 2,cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 2,     cqtDepth + 1, 0, 0, 2,treeType, modeType )   if( y1 < pic_height_in_luma_samples && x1 <pic_width_in_luma_samples )    coding_tree( x1, y1, cbWidth / 2,cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 2,     cqtDepth + 1, 0, 0, 3,treeType, modeType )   }   

 

 

 = =

  

 

 

 

 

    

 

  

 } else  coding_unit( x0, y0, cbWidth, cbHeight, cqtDepth, treeTypeCurr,modeTypeCurr ) }

2.14.1.1 Coding Unit Syntax

coding_unit( x0,y0,cbWidth, cbHeight, cqtDepth, treeType, modeType) {Descriptor  chType = treeType= = DUAL_TREE_CHROMA? 1 : 0  if( slice_type!= I | | sps_ibc_enabled_flag | | sps_palette_enabled_flag) {   if(treeType != DUAL_TREE_CHROMA &&   !( ( ( cbWidth = = 4 && cbHeight = = 4) | | modeType = = MODE_TYPE_   INTRA ) && !sps_ibc_enabled_flag))  cu_skip_flag[ x0 ][ y0 ] ae(v)   if( cu_skip_flag[ x0 ][ y0 ] = = 0 &&slice_type != I   && !( cbWidth = = 4 && cbHeight = = 4 ) && modeType == MODE_   TYPE_ALL)   pred_mode_flag ae(v)   if( ( ( slice_type = = I &&cu_skip_flag[ x0 ][ y0 ] = =0 ) | |   ( slice_type != I && ( CuPredMode[chType ][ x0 ][ y0 ] != MODE_   INTRA | | ( cbWidth = = 4 && cbHeight == 4 && cu_skip_flag[ x0 ][ y0 ]   = = 0 ) ) ) ) && cbWidth <= 64 &&cbHeight <= 64 && modeType !=   MODE_TYPE_INTER && sps_ibc_enabled_flag&& treeType != DUAL_   TREE_CHROMA)   pred_mode_ibc_flag ae(v)   if( ( (( slice_type = = I | | ( cbWidth = = 4 && cbHeight = = 4 ) | | sps_ibc_   enabled_flag ) && CuPredMode[ x0 ][ y0 ] = = MODE_INTRA) | |    (slice_type != I && !( cbWidth = = 4 && cbHeight = = 4 ) && !sps_   ibc_enabled_flag && CuPredMode[ x0 ][ y0 ] != MODE_INTRA))    &&sps_palette_enabled_flag && cbWidth <= 64 && cbHeight <= 64    && &&cu_skip_flag[ x0 ][ y0 ] = = 0 && modeType != MODE_    INTER)   pred_mode_plt_flag ae(v)   } ...

-   -   -   

        -   

    -   -   

        -   

        -   

    -   -   

        -   

    -   

Allowed Quad Split Process

Inputs to this process are:

-   -   a coding block size cb Size in luma samples,    -   a multi-type tree depth mttDepth,    -   a variable treeType specifying whether a single tree        (SINGLE_TREE) or a dual tree is used to partition the CTUs and,        when a dual tree is used, whether the luma (DUAL_TREE_LUMA) or        chroma components (DUAL_TREE_CHROMA) are currently processed,    -           Output of this process is the variable allowSplitQt.        The variable allowSplitQt is derived as follows:    -   If one or more of the following conditions are true,        allowSplitQt is set equal to FALSE:        -   treeType is equal to SINGLE_TREE or DUAL_TREE_LUMA and            cbSize is less than or equal to MinQtSizeY

        -   treeType is equal to DUAL_TREE_CHROMA and cbSize/SubWidthC            is less than or equal to MinQtSizeC

        -   mttDepth is not equal to 0

        -   treeType is equal to DUAL_TREE_CHROMA and (cbSize/SubWidthC)            is less than or equal to 4

        -       -   Otherwise, allowSplitQt is set equal to TRUE.

Allowed Binary Split Process

Inputs to this process are:

-   -   a binary split mode btSplit,    -   a coding block width cbWidth in luma samples,    -   a coding block height cbHeight in luma samples,    -   a location (x0, y0) of the top-left luma sample of the        considered coding block relative to the top-left luma sample of        the picture,    -   a multi-type tree depth mttDepth,    -   a maximum multi-type tree depth with offset maxMttDepth,    -   a maximum binary tree size maxBtSize,    -   a minimum quadtree size minQtSize,    -   a partition index partIdx,    -   a variable treeType specifying whether a single tree        (SINGLE_TREE) or a dual tree is used to partition the CTUs and,        when a dual tree is used, whether the luma (DUAL_TREE_LUMA) or        chroma components (DUAL_TREE_CHROMA) are currently processed,    -           Output of this process is the variable allowBtSplit.

TABLE 6-2 Specification of parallelTtSplit and cbSize based on btSplit.btSplit = = btSplit = = SPLIT_BT_VER SPLIT_BT_HOR parallelTtSplitSPLIT_TT_VER SPLIT_TT_HOR cbSize cbWidth cbHeightThe variables parallelTtSplit and cb Size are derived as specified inTable 6-2.The variable allowBtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowBtSplit is set equal to FALSE:        -   cb Size is less than or equal to MinBtSizeY

        -   cbWidth is greater than maxBtSize

        -   cbHeight is greater than maxBtSize

        -   mttDepth is greater than or equal to maxMttDepth

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 16

        -       -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   btSplit is equal to SPLIT_BT_VER        -   y0+cbHeight is greater than pic_height_in_luma_samples    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   btSplit is equal to SPLIT_BT_VER        -   cbHeight is greater than MaxTbSizeY        -   x0+cbWidth is greater than pic_width_in_luma_samples    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   btSplit is equal to SPLIT_BT_HOR        -   cbWidth is greater than MaxTbSizeY        -   y0+cbHeight is greater than pic_height_in_luma_samples    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   x0+cbWidth is greater than pic_width_in_luma_samples        -   y0+cbHeight is greater than pic_height_in_luma_samples        -   cbWidth is greater than minQtSize    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   btSplit is equal to SPLIT_BT_HOR        -   x0+cbWidth is greater than pic_width_in_luma_samples        -   y0+cbHeight is less than or equal to            pic_height_in_luma_samples    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE:        -   mttDepth is greater than 0        -   partIdx is equal to 1        -   MttSplitMode[x0][y0][mttDepth−1] is equal to parallelTtSplit    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   btSplit is equal to SPLIT_BT_VER        -   cbWidth is less than or equal to MaxTbSizeY        -   cbHeight is greater than MaxTbSizeY    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   btSplit is equal to SPLIT_BT_HOR        -   cbWidth is greater than MaxTbSizeY        -   cbHeight is less than or equal to MaxTbSizeY    -   Otherwise, allowBtSplit is set equal to TRUE.

Allowed Ternary Split Process

Inputs to this process are:

-   -   a ternary split mode ttSplit,    -   a coding block width cbWidth in luma samples,    -   a coding block height cbHeight in luma samples,    -   a location (x0, y0) of the top-left luma sample of the        considered coding block relative to the top-left luma sample of        the picture,    -   a multi-type tree depth mttDepth    -   a maximum multi-type tree depth with offset maxMttDepth,    -   a maximum ternary tree size maxTtSize,    -   a variable treeType specifying whether a single tree        (SINGLE_TREE) or a dual tree is used to partition the CTUs and,        when a dual tree is used, whether the luma (DUAL_TREE_LUMA) or        chroma components (DUAL_TREE_CHROMA) are currently processed,    -           Output of this process is the variable allowTtSplit.

TABLE 6-3 Specification of cbSize based on ttSplit. ttSplit = =SPLIT_TT_VER ttSplit = = SPLIT_TT_HOR cbSize cbWidth cbHeightThe variable cb Size is derived as specified in Table 6-3.The variable allowTtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowTtSplit is set equal to FALSE:        -   cb Size is less than or equal to 2*MinTtSizeY

        -   cbWidth is greater than Min(MaxTbSizeY, maxTtSize)

        -   cbHeight is greater than Min(MaxTbSizeY, maxTtSize)

        -   mttDepth is greater than or equal to maxMttDepth

        -   x0+cbWidth is greater than pic_width_in_luma_samples

        -   y0+cbHeight is greater than pic_height_in_luma_samples

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 32

        -   

    -   Otherwise, allowTtSplit is set equal to TRUE.        pred_mode_flag equal to 0 specifies that the current coding unit        is coded in inter prediction mode.        pred_mode_flag equal to 1 specifies that the current coding unit        is coded in intra prediction mode.        When pred_mode_flag is not present, it is inferred as follows:

    -   If cbWidth is equal to 4 and cbHeight is equal to 4,        pred_mode_flag is inferred to be equal to 1.

    -   

    -   

    -   Otherwise, pred_mode_flag is inferred to be equal to 1 when        decoding an I slice, and equal to 0 when decoding a P or B        slice, respectively.        The variable CuPredMode[chType][x][y] is derived as follows for        x=x0 . . . x0+cbWidth−1 and y=y0 . . . y0+cbHeight−1:

    -   If pred_mode_flag is equal to 0, CuPredMode[chType][x][y] is set        equal to MODE_INTER.

    -   Otherwise (pred_mode_flag is equal to 1),        CuPredMode[chType][x][y] is set equal to MODE_INTRA.        pred_mode_ibc_flag equal to 1 specifies that the current coding        unit is coded in IBC prediction mode. pred_mode_ibc_flag equal        to 0 specifies that the current coding unit is not coded in IBC        prediction mode.        When pred_mode_ibc_flag is not present, it is inferred as        follows:

    -   If cu_skip_flag[x0][y0] is equal to 1, and cbWidth is equal to        4, and cbHeight is equal to 4, pred_mode_ibc_flag is inferred to        be equal 1.

    -   Otherwise, if both cbWidth and cbHeight are equal to 128,        pred_mode_ibc_flag is inferred to be equal to 0.

    -   

    -   

    -   Otherwise, pred_mode_ibc_flag is inferred to be equal to the        value of sps_ibc_enabled_flag when decoding an I slice, and 0        when decoding a P or B slice, respectively.        When pred_mode_ibc_flag is equal to 1, the variable        CuPredMode[chType][x][y] is set to be equal to MODE_IBC for x=x0        . . . x0+cbWidth−1 and y=y0 . . . y0+cbHeight−1.

3. EXAMPLES OF TECHNICAL PROBLEMS SOLVED BY DISCLOSED TECHNICALSOLUTIONS

-   -   1. Currently IBC is considered as MODE_TYPE_INTRA and thus small        chroma block is disallowed, which leads to unnecessary coding        efficiency loss.    -   2. Currently palette is considered as MODE_TYPE_INTRA and thus        small chroma block is disallowed, which leads to unnecessary        coding efficiency loss.    -   3. Currently small chroma block constrains do not consider color        subsampling format.    -   4. Currently same partition and prediction mode constraints on        small blocks is applied to all chroma formats. However, it may        be desirable to design different constraint mechanisms on small        blocks in 4:2:0 and 4:2:2 chroma formats.    -   5. Currently the Palette mode flag signaling depends on the        modeType, which is not desirable as palette may be not apply        small block constraints.    -   6. Currently the IBC mode flag is inferred to be 0 for PB slice        with cu_skip_flag equal to 1 but MODE_TYPE equal to        MODE_TYPE_INTRA, this is illegal in the syntax parsing.    -   7. Currently, non-4×4 luma IBC mode is not allowed for SCIPU        luma blocks, which may be not desirable and may cause coding        efficiency loss.    -   8. 2×H chroma block is still allowed, which is not friendly to        hardware implementation.    -   9. CIIP is considered as of MODE_INTER while it uses intra        prediction, which breaks the constrains in some cases.    -   10. When SCIPU is applied, delta QP for chroma may be signaled        depending on the luma splitting. For example, when the current        block dimensions are 16×8 in luma samples and are split with        vertical TT, a local dual tree may be applied. It is specified        that qgOnC=qgOnC && (cbSubdiv+2<=cu_chroma_qp_offset_subdiv) So        qgOnC is set to zero if cbSubdiv+2<=cu_chroma_qp_offset_subdiv.        This conditional setting assumes that the chroma component is        also split by TT. With the local dual tree, the chroma component        may not be split, thus cbSubdiv may be larger than        cu_chroma_qp_offset_subdiv. IsCuChromaQpOffsetCoded should be        set to be 0 to allow signaling delta QP for chroma. However,        IsCuChromaQpOffsetCoded is not set to be 0 because qgOnC is set        to be 0.

4. EXAMPLES OF TECHNICAL SOLUTIONS AND EMBODIMENTS

The listing below should be considered as examples. These techniquesshould not be interpreted in a narrow way. Furthermore, these techniquescan be combined in any manner.

In this document, “M×N coding tree node” indicates a M×N block, with Mas the block width and N as the block height in luma samples, which maybe further partitioned, such as by QT/BT/TT. For example, a block couldbe a QT node, or a BT node, or a TT node. A coding tree node could be acoding unit (e.g., with three color components for single tree, with twochroma color components for dual tree chroma coding, and only luma colorcomponent for dual tree luma coding), or a luma coding block, or achroma coding block. A “small coding tree node unit” may indicate acoding tree node with block size M×N equal to 32/64/128 in luma samples.

If not specifically mentioned, the width W and height H for a codingblock is measured in luma samples. For example, M×N coding block means aM×N luma block, and/or two (M/SubWidthC)×(N/SubHeightC) chroma blocks,where SubWidthC and SubHeightC are derived by chroma format as below.

chroma_ separate_colour_ Chroma SubWidth SubHeight format_idc plane_flagformat C C 0 0 Mono- 1 1 chrome 1 0 4:2:0 2 2 2 0 4:2:2 2 1 3 0 4:4:4 11 3 1 4:4:4 1 1

-   1. Whether and/or how to partition into small blocks may depend on    color formats.    -   a. In one example, for 4:4:4 color format, the constrains on the        sizes of chroma blocks may follow those constrains on luma        blocks.    -   b. In one example, for 4:2:2 color format, the constrains on the        sizes of chroma blocks may follow those constrains for 4:2:0        color format.    -   c. In one example, for 4:0:0, and/or 4:4:4 chroma format, the        constraints on small block partitions and/or prediction modes        may be not applied.    -   d. In one example, the constraints on small block partitions        and/or prediction modes may be applied differently for different        chroma formats.        -   i. In one example, for M×N (such as 8×8) coding tree node            with horizontal BT split, in 4:2:2 chroma format, the            horizontal BT split may be allowed for both chroma block and            luma block, while in 4:2:0 chroma format, the horizontal BT            split may be allowed for luma block but disabled for chroma            block.        -   ii. In one example, for M×N (such as 16×4) coding tree node            with vertical BT split, in 4:2:2 chroma format, the vertical            BT split may be allowed for both chroma block and luma            block, while in 4:2:0 chroma format, the vertical BT split            may be allowed for luma block but disabled for chroma block.        -   iii. In one example, for M×N (such as 8×16) coding tree node            with horizontal TT split, in 4:2:2 chroma format, the            horizontal TT split may be allowed for both chroma block and            luma block, while in 4:2:0 chroma format, the horizontal TT            split may be allowed for luma block but disabled for chroma            block.        -   iv. In one example, for M×N (such as 32×4) coding tree node            with vertical TT split, in 4:2:2 chroma format, the vertical            TT split may be allowed for both chroma block and luma            block, while in 4:2:0 chroma format, the vertical TT split            may be allowed for luma block but disabled for chroma block.        -   v. In one example, for 4:0:0, and/or 4:4:4 color formats,            small block constraints may be not applied.    -   e. In one example, whether to enable SCIPU is dependent on the        color format.        -   i. In one example, SCIPU is enabled for 4:2:0 and 4:2:2            color formats.        -   ii. In one example, SCIPU is disabled for 4:0:0 and/or 4:4:4            color format.            -   1. In one example, modeType may be always equal to                MODE_TYPE_ALL for 4:0:0 and/or 4:4:4 color format.            -   2. In one example, modeTypeCondition may be always equal                to 0 for 4:0:0 and/or 4:4:4 color format.-   2. How to determine the prediction modes (and/or modeType) for    (sub-)blocks of a coding tree node may depend on chroma formats.    -   a. In one example, if one of the below conditions is true, the        modeType of (sub-)blocks partitioned by this coding tree node        may be equal to MODE_TYPE_ALL for 4:2:2 chroma format, while for        4:2:0 chroma format, the modeType may be equal to either        MODE_TYPE_INTRA or MODE_TYPE_INTER.        -   i. M×N (such as 8×8) coding tree node with horizontal BT            split        -   ii. M×N (such as 16×4) coding tree node with vertical BT            split        -   iii. M×N (such as 8×16) coding tree node with horizontal TT            split        -   iv. M×N (such as 32×4) coding tree node with vertical TT            split-   3. It is proposed to rename MODE_TYPE_INTRA to MODE_TYPE_NO_INTER    and restrict the usage of MODE_INTER.    -   a. In one example, when modeType of a coding unit is equal to        MODE_TYPE_NO_INTER, MODE_INTER may be disallowed.-   4. It is proposed to rename MODE_TYPE_INTER to MODE_TYPE_NO_INTRA    and restrict the usage of MODE_INTRA.    -   a. In one example, when modeType of a coding unit is equal to        MODE_TYPE_NO_INTRA, MODE_INTRA may be disallowed.-   5. The mode constraint flag may be never signaled in 4:2:2 and/or    4:0:0 and/or 4:4:4 chroma formats.    -   a. In one example, when mode constraint flag is not present, it        may be inferred to equal to be 1.        -   i. Alternatively, when mode constraint flag is not present,            it may be inferred to equal to be 0.-   6. Whether and/or how to apply SCIPU on an M×N coding block with M    as the block width and N as the block height may depend on whether    the color format is 4:2:0 or 4:2:2.    -   a. In one example, in 4:2:2 color format, for an M×N coding        block with M as the block width and N as the block height, SCIPU        may be enabled only if M multiplied by N (denoted by M*N) is        equal to 64 or 32.    -   b. In one example, a coding tree node with M*N=128 may be never        treated as SCIPU block in 4:2:2 color format.    -   c. In one example, a coding tree node with BT split and M*N=64        may be never treated as SCIPU block in 4:2:2 color format.    -   d. In one example, a coding tree node with split_qt_flag equal        to 1 and M*N=64, may be an SCIPU block in 4:2:2 color format.    -   e. In one example, a coding tree node with TT split and M*N=64,        may be treated as SCIPU block in 4:2:2 color format.    -   f. In one example, a coding tree node with BT split and M*N=32,        may be treated as SCIPU block in 4:2:2 color format.    -   g. In above description, for an SCIPU block in 4:2:2 color        format, the modeTypeCondition may be always equal to 1.    -   h. In above description, for an SCIPU block in 4:2:2 color        format, only MODE_TYPE_INTRA may be allowed for both the current        block in parent node and all sub-blocks under child leaf nodes.-   7. In 4:2:2 color format, modeTypeCondition of an SCIPU block may be    always equal to 1.    -   a. In one example, modeTypeCondition may be equal to 0 or 1 for        4:2:2 color format.    -   b. In one example, for SCIPU blocks in 4:2:2 color format,        modeTypeCondition may be never equal to 2.-   8. In 4:2:2 color format, modeType of an SCIPU block may be always    equal to MODE_TYPE_INTRA.    -   a. In one example, modeType may be equal to MODE_TYPE_ALL or        MODE_TYPE_INTRA in 4:2:2 color format.    -   b. In one example, for SCIPU blocks in 4:2:2 color format,        MODE_TYPE_INTER may be disabled.-   9. Whether the block partition is allowed or not may be dependent on    the modeType, and/or the block size.    -   a. In one example, whether BT and/or TT split is allowed for a        block may be dependent on the modeType.        -   i. In one example, if modeType is equal to MODE_TYPE_INTER,            then BT split may be disallowed for the current coding block            (e.g., allowBtSplit is set equal to false).        -   ii. In one example, if modeType is equal to MODE_TYPE_INTER,            then TT split may be disallowed for the current coding block            (e.g., allowTtSplit is set equal to false).    -   b. In one example, whether BT and/or TT split is allowed for a        block may be dependent on the modeType and the block size.        -   i. In one example, for an M×N coding block, with M as the            block width and N as the block height, when M*N is less than            or equal to 32 and modeType is equal to MODE_TYPE_INTER, the            BT split may be disallowed (e.g., allowBtSplit is set equal            to false).        -   ii. In one example, for an M×N coding block, with M as the            block width and N as the block height, when M*N is less than            or equal to 64 and modeType is equal to MODE_TYPE_INTER, the            TT split may be disallowed (e.g., allowTtSplit is set equal            to false).-   10. When modeTypeCurr of a coding tree is equal to MODE_TYPE_INTER,    split of the coding tree may be restricted    -   a. In one example, when modeTypeCurr of a coding tree is equal        to MODE_TYPE_INTER, BT split may be disallowed.    -   b. In one example, when modeTypeCurr of a coding tree is equal        to MODE_TYPE_INTER, TT split may be disallowed.    -   c. In one example, when modeTypeCurr of a coding tree is equal        to MODE_TYPE_INTER, QT split may be disallowed.    -   d. In one example, when modeTypeCurr of a coding tree is equal        to MODE_TYPE_INTER and luma block size is less than or equal to        32, BT split may be disallowed.    -   e. In one example, when modeTypeCurr of a coding tree is equal        to MODE_TYPE_INTER and luma block size is less than or equal to        64, TT split may be disallowed.-   11. A coding unit with treeType being DUAL_TREE_LUMA may be coded in    inter mode.    -   a. In one example, coding unit coded in inter coding mode, i.e.        MODE_INTER may only contain luma component even for color        formats with multiple color components.    -   b. In one example, pred_mode_flag may need to be parsed for        DUAL_TREE_LUMA block.    -   c. In one example, for DUAL_TREE_LUMA block coded in inter mode,        the same constrains of inter mode for SINGLE_TREE may be also        applied.        -   i. In one example, 4×4 DUAL_TREE_LUMA inter block may be            disallowed.-   12. Chroma intra (and/or IBC) blocks with block width equal to M    (such as M=2) chroma samples may be not allowed.    -   a. In one example, 2×N (such as N<=64) chroma intra blocks may        be not allowed in dual tree.        -   i. In one example, when treeType is equal to            DUAL_TREE_CHROMA and the block width is equal to 4 chroma            samples, vertical BT split may be disabled.        -   ii. In one example, when treeType is equal to            DUAL_TREE_CHROMA and the block width is equal to 8 chroma            samples, vertical TT split may be disabled.    -   b. In one example, 2×N (such as N<=64) chroma intra (and/or IBC)        blocks may be not allowed in single tree.        -   i. In one example, for M×N (such as M=8 and N<=64) coding            tree node with vertical BT split, one of below process may            be applied.            -   1. Vertical BT split may be disallowed for the 4×N or                4×(N/2) chroma block but allowed for the 8×N luma block.            -   2. The 4×N or 4×(N/2) chroma block may be not vertical                BT split, and it may be coded by MODE_INTRA, or                MODE_IBC.            -   3. Vertical BT split may be allowed for both the 8×N                luma block and the 4×N or 4×(N/2) chroma block, but both                luma and chroma blocks not coded by MODE_INTRA (e.g.,                may be coded by MODE_INTER, or MODE_IBC).        -   ii. In one example, for M×N (such as M=16 and N<=64) coding            tree node with vertical TT split, one of below process may            be applied.            -   1. Vertical TT split may be disallowed for the 8×N or                8×(N/2) chroma block but allowed for the 16×N luma                block.            -   2. The 8×N or 8×(N/2) chroma block may be not vertical                TT split and coded by MODE_INTRA, or MODE_IBC.            -   3. Vertical TT split may be allowed for both the 16×N                luma block and the 8×N or 8×(N/2) chroma block, but both                luma and chroma blocks may be not coded by MODE_INTRA                (e.g., may be coded by MODE_INTER, or MODE_IBC).-   13. IBC mode may be allowed for luma and/or chroma blocks regardless    of whether it is of small block size.    -   a. In one example, IBC mode may be allowed for luma blocks        including 8×4/8×8/16×4 and 4×N (such as N<=64) luma blocks, even        if modeType is equal to MODE_TYPE_INTRA.    -   b. In one example, IBC mode may be allowed for chroma blocks,        even if modeType is equal to MODE_TYPE_INTRA.-   14. The signaling of IBC prediction mode flag may depend on    prediction mode type (e.g., MODE_TYPE_INTRA).    -   a. In one example, IBC prediction mode flag for a non-SKIP block        (e.g. a coding block which is not coded by skip mode) may be        explicitly signaled in the bitstream when the treeType is not        equal to DUAL_TREE_CHROMA and the modeType is equal to        MODE_TYPE_INTRA.-   15. IBC prediction mode flag may be inferred depending on the CU    SKIP flag and the mode type (e.g., modeType).    -   a. In one example, if the current block is coded with SKIP mode        (such as cu_skip_flag is equal to 1), and the modeType is equal        to MODE_TYPE_INTRA, the IBC prediction mode flag (such as        pred_mode_ibc_flag) may be inferred to be equal to 1.-   16. The explicit signaling of Palette mode flag may not depend on    the modeType.    -   a. In one example, palette mode flag (such as        pred_mode_plt_flag) signaling may depend on the slice type,        block size, prediction mode, etc., But no matter what the        modeType is.    -   b. In one example, palette mode flag (such as        pred_mode_plt_flag) is inferred to be 0 when modeType is equal        to MODE_TYPE_INTER or MODE_TYPE_INTRA.-   17. IBC mode may be allowed to use when modeType is equal to    MODE_TYPE_INTER    -   a. In one example, chroma IBC may be disallowed when modeType is        equal to MODE_TYPE_INTRA.    -   b. In one example, IBC mode may be allowed to use when modeType        is equal to MODE_TYPE_INTRA or MODE_TYPE_INTER.    -   c. In one example, IBC mode may be allowed to use regardless        what modeType is.    -   d. In one example, within one SCIPU, IBC and inter mode may be        both allowed.    -   e. In one example, the size of IBC chroma block may always        corresponds to the size of corresponding luma block.    -   f. In one example, when modeType is equal to MODE_TYPE_INTER and        coding unit size is 4×4 in luma, signaling of pred_mode_ibc_flag        may be skipped and pred_mode_ibc_flag may be inferred to be        equal to 1.-   18. Palette mode may be allowed to use when modeType is    MODE_TYPE_INTER    -   a. In one example, chroma palette may be disallowed when        modeType is MODE_TYPE_INTRA.    -   b. In one example, IBC mode may be allowed to use when modeType        is equal to MODE_TYPE_INTRA or MODE_TYPE_INTER.    -   c. In one example, IBC mode may be allowed to use regardless        what modeType is.    -   d. In one example, palette mode may be allowed to use when        modeType is equal to MODE_TYPE_INTRA or MODE_TYPE_INTER.    -   e. In one example, palette mode may be allowed to use regardless        what modeType is.    -   f. In one example, within one SCIPU, palette and inter mode may        be both allowed.    -   g. In one example, within one SCIPU, palette, IBC and inter mode        may be all allowed.    -   h. In one example, the size of palette chroma block may always        corresponds to the size of corresponding luma block.    -   i. In one example, when modeType is equal to MODE_TYPE_INTER and        coding unit size is 4×4 in luma, signaling of pred_mode_plt_flag        may be skipped and pred_mode_plt_flag may be inferred to be        equal to 1.    -   j. In one example, when modeType is equal to MODE_TYPE_INTER and        coding unit size is 4×4 in luma, one message may be sent to        indicated if the current prediction mode is of IBC or palette.    -   k. In one example, whether to enable/disable Palette mode may        depend on slice types and modeType.        -   i. In one example, for I slices with MODE_TYPE_INTRA,            Palette mode may be enabled.        -   ii. In one example, for PB slices with MODE_TYPE_INTER,            Palette mode may be enabled.-   19. When palette mode is enabled, local dualtree may be disallowed.    -   a. In one example, when palette mode is enabled,        modeTypeCondition may be always set equal to 0.-   20. For small chroma blocks with width equal to M (e.g., M=2) or    height equal to N (e.g., N=2), allowed intra prediction modes may be    restricted to be different from those allowed for large chroma    blocks.    -   a. In one example, only a subset of intra prediction mode of        available chroma intra prediction modes may be used.    -   b. In one example, only INTRA_DC mode may be used.    -   c. In one example, only INTRA_PLANAR mode may be used.    -   d. In one example, only INTRA_ANGULAR18 mode may be used.    -   e. In one example, only INTRA_ANGULAR50 mode may be used.    -   f. In one example, CCLM modes may be disallowed.-   21. For small chroma blocks with width equal to M (e.g., M=2) or    height equal to N (e.g., N=2), transform types may be restricted to    be different from those allowed for large chroma blocks.    -   a. In one example, only transform skip may be used.    -   b. In one example, only one-dimensional transform may be used.    -   c. In one example, coding tools that support multiple types of        transforms are disallowed.        -   i. Alternatively, the signaling of coding tools that support            multiple types of transforms is omitted.-   22. CIIP may be considered as MODE_TYPE_INTRA.    -   a. In one example, CIIP mode may be allowed when dualtree        partitioning is used.        -   i. In one example, CIIP mode may be allowed when CU type is            of DUAL_TREE_CHROMA.    -   b. Alternatively, CIIP may be considered as MODE_TYPE_INTER        -   i. In one example, when chroma block width is equal to M            (e.g., M=2), CIIP mode may be disallowed.        -   ii. In one example, when chroma block width is equal to M            (e.g., M=2), intra prediction modes for chroma in CIIP may            be restricted to simple intra prediction mode.            -   1. In one example, INTRA_DC may be used for chroma intra                prediction, when chroma block width is equal to M (e.g.,                M=2).            -   2. In one example, INTRA_ANGULAR18 may be used for                chroma intra prediction, when chroma block width is                equal to M (e.g., M=2).            -   3. In one example, INTRA_ANGULAR50 may be used for                chroma intra prediction, when chroma block width is                equal to M (e.g., M=2).        -   iii. In one example, intra prediction modes for chroma in            CIIP may be restricted to simple intra prediction mode.            -   1. In one example, INTRA_DC may be used for chroma intra                prediction.            -   2. In one example, INTRA_ANGULAR18 mode may be used for                chroma intra prediction.            -   3. In one example, INTRA_ANGULAR50 mode may be used for                chroma intra prediction.-   23. For above bullets, the variables M and/or N may be pre-defined    or signaled.    -   a. In one example, M and/or N may be further dependent on color        formats (e.g., 4:2:0, 4:2:2, 4:4:4).-   24. modeType may be extended to cover more types.    -   a. In one example, modeType may be MODE_TYPE_IBC. When modeType        is equal to MODE_TYPE_IBC, the prediction mode is inferred to be        IBC.        -   i. In one example, pred_mode_flag is not signaled in this            case.        -   ii. In one example, pred_mode_ibc_flag is not signaled in            this case.        -   iii. In one example, pred_mode_plt_flag is not signaled in            this case.    -   b. In one example, modeType may be MODE_TYPE_PALETTE. When        modeType is equal to MODE_TYPE_PALETTE, the prediction mode is        inferred to be Palette mode.        -   i. In one example, pred_mode_flag is not signaled in this            case.        -   ii. In one example, pred_mode_ibc_flag is not signaled in            this case.        -   iii. In one example, pred_mode_plt_flag is not signaled in            this case.    -   c. In one example, mode_constraint_flag may be replaced by an        index to tell which one of allowed modeTypes are used.-   25. In one example, whether QT split is allowed fora block with    dimensions W×H may depend on modeType combined with dimensions.    -   a. For example, if modeType is equal to MODE_TYPE_INTER and W is        equal to 8 and

H is equal to 8, QT spit is disallowed.

-   26. In one example, whether vertical TT split is allowed for a block    with dimensions W×H may depend on modeType combined with dimensions.    -   a. For example, if modeType is equal to MODE_TYPE_INTER and W is        equal to 16 and H is equal to 4, vertical TT spit is disallowed.-   27. In one example, whether horizontal TT split is allowed for a    block with dimensions W×H may depend on modeType combined with    dimensions.    -   a. For example, if modeType is equal to MODE_TYPE_INTER and W is        equal to 4 and H is equal to 16, horizontal TT spit is        disallowed.-   28. In one example, whether vertical BT split is allowed fora block    with dimensions W×H may depend on modeType combined with dimensions.    -   a. For example, if modeType is equal to MODE_TYPE_INTER and W is        equal to 8 and H is equal to 4, vertical BT spit is disallowed.-   29. In one example, whether horizontal BT split is allowed for a    block with dimensions W×H may depend on modeType combined with    dimensions.    -   a. For example, if modeType is equal to MODE_TYPE_INTER and W is        equal to 4 and H is equal to 8, horizontal BT spit is        disallowed.-   30. In one example, whether the prediction mode of a CU is inferred    by modeType may depend on color components and/or block dimensions    W×H.    -   a. For example, the prediction mode of a chroma CU is inferred        by modeType; but the prediction mode of a luma CU is signaled        instead of inferred by modeType.        -   i. For example, the prediction mode of a luma CU is signaled            instead of inferred by modeType if W>4 or H>4.-   31. When SCIPU is applied, whether to and/or how to signal the    information related to delta QP of a first component may depend on    the splitting way of the first component.    -   a. In one example, when SCIPU is applied, whether to and/or how        to signal the information related to delta QP of a first        component may depend on the splitting way of the first component        and decoupled from the splitting way of a second component.    -   b. In one example, the first component is luma and the second        component is chroma.    -   c. In one example, the first component is chroma and the second        component is luma.-   32. Any variable related to delta QP of a first component cannot be    modified during the decoding or parsing process of a second    component when dual tree and/or local dual tree coding structure is    applied.    -   a. In one example, the local dual tree coding structure may be        used according to SCIPU.    -   b. In one example, the first component is luma and the second        component is chroma.        -   i. The variable may be IsCuQpDeltaCoded.    -   c. In one example, the first component is chroma and the second        component is luma.        -   i. The variable may be IsCuChromaQpOffsetCoded.-   33. When SCIPU is applied, the information related to delta QP of a    component (such as luma or chroma) may be signaled at most once in a    specific region wherein the luma component and the chroma component    are required to share the same mode type (such as MODE_TYPE_INTER or    MODE_TYPE_INTRA).    -   a. In one example, the specific region is a regarded as a        quantization group.

5. EMBODIMENTS

Newly added parts are highlighted in bold and Italic, and the deletedparts from VVC working draft are marked with double brackets (e.g.,[[a]] denotes the deletion of the character ‘a’). The modifications arebased on the latest VVC working draft (JVET-O2001-v11)

5.1 An Example Embodiment #1

The embodiment below is about the constraints on small block partitionsand prediction modes are applied to 4:2:0 and 4:4:4 chromaformats only(not apply to 4:0:0 and 4:4:4 chroma formats).

7.4.9.4 Coding Tree Semantics

The variable modeTypeCondition is derived as follows:

-   -   If one of the following conditions is true, modeTypeCondition is        set equal to 0        -   slice_type==I and qtbtt_dual_tree_intra_flag is equal to 1

        -   modeTypeCurr is not equal to MODE_TYPE_ALL

        -   

        -       -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1        -   cbWidth*cbHeight is equal to 64 and split_qt_flag is equal            to 1        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER        -   cbWidth*cbHeight is equal to 32 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1+(slice_type!=I? 1:0)        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER        -   cbWidth*cbHeight is equal to 128 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER    -   Otherwise, modeTypeCondition is set equal to 0

5.2 An Example Embodiment #2

The embodiment below is about the signaling of Palette mode flag notdepend on the modeType.

7.3.8.5 Coding Unit Syntax

coding_unit( x0, y0, cbWidth, cbHeight, cqtDepth, treeType, modeType ) {Descriptor  chType = treeType = = DUAL_TREE_CHROMA? 1 : 0  if(slice_type != I ∥ sps_ibc_enabled_flag ∥  sps_palette_enabled_flag) {  if( treeType != DUAL_TREE_CHROMA &&    !( ( ( cbWidth = = 4 &&cbHeight = = 4 ) ∥    modeType = = MODE_TYPE_INTRA )     &&!sps_ibc_enabled_flag ) )    cu_skip_flag[ x0 ][ y0 ] ae(v)   if(cu_skip_flag[ x0 ][ y0 ] = = 0 && slice_type != I    && !( cbWidth = = 4&& cbHeight = = 4 ) &&    modeType = = MODE_TYPE_ALL )    pred_mode_flagae(v)   if( ( ( slice_type = = I && cu_skip_flag   [ x0 ][ y0 ] = =0 ) ∥    ( slice_type != I && ( CuPredMode     [ chType ][ x0 ][ y0 ] !=MODE_INTRA ∥      ( cbWidth = = 4 && cbHeight = = 4 &&     cu_skip_flag[ x0 ][ y0 ] = = 0 ) ) ) ) &&     cbWidth <= 64 &&cbHeight <= 64 &&     modeType != MODE_TYPE_INTER &&    sps_ibc_enabled_flag && treeType !=     DUAL_TREE_CHROMA )   pred_mode_ibc_flag ae(v)   if( ( ( ( slice_type = = I ∥ ( cbWidth = =4 &&   cbHeight = = 4 ) ∥ sps_ibc_enabled_flag ) &&       CuPredMode[ x0][ y0 ] = = MODE_INTRA ) ∥     ( slice_type != I && !( cbWidth = = 4 &&cbHeight = = 4 ) && !sps_ibc_enabled_flag      && CuPredMode[ x0 ][ y0 ]!= MODE_INTRA ) ) && sps_palette_enabled_flag &&     cbWidth <= 64 &&cbHeight <= 64 && &&     cu_skip_flag[ x0 ][ y0 ] = = 0 [[&&    modeType != MODE_INTER]] )    pred_mode_plt_flag ae(v)

5.3 An Example Embodiment #3

The embodiment below is about the IBC prediction mode flag is inferreddepending on the CU SKIP flag and the modeType.pred_mode_ibc_flag equal to 1 specifies that the current coding unit iscoded in IBC prediction mode. pred_mode_ibc_flag equal to 0 specifiesthat the current coding unit is not coded in IBC prediction mode.When pred_mode_ibc_flag is not present, it is inferred as follows:

-   -   If cu_skip_flag[x0][y0] is equal to 1, and cbWidth is equal to        4, and cbHeight is equal to 4, pred_mode_ibc_flag is inferred to        be equal 1.

    -   Otherwise, if both cbWidth and cbHeight are equal to 128,        pred_mode_ibc_flag is inferred to be equal to 0.

    -   

    -   Otherwise, if modeType is equal to MODE_TYPE_INTER,        pred_mode_ibc_flag is inferred to be equal to 0.

    -   Otherwise, if treeType is equal to DUAL_TREE_CHROMA,        pred_mode_ibc_flag is inferred to be equal to 0.

    -   Otherwise, pred_mode_ibc_flag is inferred to be equal to the        value of sps_ibc_enabled_flag when decoding an I slice, and 0        when decoding a P or B slice, respectively.        When pred_mode_ibc_flag is equal to 1, the variable        CuPredMode[chType][x][y] is set to be equal to MODE_IBC for x=x0        . . . x0+cbWidth−1 and y=y0 . . . y0+cbHeight−1.

5.4 An Example Embodiment #4

The embodiment below is about the signaling of IBC prediction mode flagdepend on MODE_TYPE_INTRA, and/or IBC mode is allowed for luma blocksregardless of whether it is small block size.

7.3.8.5 Coding Unit Syntax

coding_unit( x0, y0, cbWidth, cbHeight, cqtDepth, treeType, modeType ) {Descriptor  chType = treeType = = DUAL_TREE_CHROMA? 1 : 0  if(slice_type != I ∥ sps_ibc_enabled_flag ∥  sps_palette_enabled_flag) {  if( treeType != DUAL_TREE_CHROMA &&    !( ( ( cbWidth = = 4 &&cbHeight = = 4 ) ∥    modeType = = MODE_TYPE_INTRA )     &&!sps_ibc_enabled_flag ) )    cu_skip_flag[ x0 ][ y0 ] ae(v)   if(cu_skip_flag[ x0 ][ y0 ] = = 0 && slice_type != I    && !( cbWidth = = 4&& cbHeight = = 4 ) &&    modeType = = MODE_TYPE_ALL )    pred_mode_flagae(v)   if( ( ( slice_type = = I && cu_skip_flag   [ x0 ][ y0 ] = =0 ) ∥    ( slice_type != I && ( CuPredMode     [ chType ][ x0 ][ y0 ] !=MODE_INTRA ∥       

        

 ∥      ( cbWidth = = 4 && cbHeight = = 4 &&      cu_skip_flag[ x0 ][ y0] = = 0 ) ) ) ) &&    cbWidth <= 64 && cbHeight <= 64 && modeType !=   MODE_TYPE_INTER &&    sps_ibc_enabled_flag && treeType !=   DUAL_TREE_CHROMA )    pred_mode_ibc_flag ae(v)

5.5 An Example Embodiment #5

The embodiment below is about applying different intra blocksconstraints for 4:2:0 and 4:2:2 color formats.

7.4.9.4 Coding Tree Semantics

The variable modeTypeCondition is derived as follows:

-   -   If one of the following conditions is true, modeTypeCondition is        set equal to 0        -   slice_type==I and qtbtt_dual_tree_intra_flag is equal to 1        -   modeTypeCurr is not equal to MODE_TYPE_ALL    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1        -   cbWidth*cbHeight is equal to 64 and split_qt_flag is equal            to 1        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER        -   cbWidth*cbHeight is equal to 32 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1+(slice_type!=I? 1:0)        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER

        -   cbWidth*cbHeight is equal to 128 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER

        -   

        -   

        -   

        -       -   Otherwise, modeTypeCondition is set equal to 0

5.6 An Example Embodiment #6

The embodiment below is about disallowing 2×N chroma intra blocks insingle tree.

7.4.9.4 Coding Tree Semantics

The variable modeTypeCondition is derived as follows:

-   -   If one of the following conditions is true, modeTypeCondition is        set equal to 0        -   slice_type==I and qtbtt_dual_tree_intra_flag is equal to 1        -   modeTypeCurr is not equal to MODE_TYPE_ALL    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1        -   cbWidth*cbHeight is equal to 64 and split_qt_flag is equal            to 1        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER        -   cbWidth*cbHeight is equal to 32 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1+(slice_type!=I? 1:0)        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER

        -   cbWidth*cbHeight is equal to 128 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER

        -   

        -       -   Otherwise, modeTypeCondition is set equal to 0

5.7 An Example Embodiment #7

The embodiment below is about disallowing 2×N chroma intra blocks indual tree.

6.4.2 Allowed Binary Split Process

The variable allowBtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowBtSplit is set equal to FALSE:        -   cb Size is less than or equal to MinBtSizeY

        -   cbWidth is greater than maxBtSize

        -   cbHeight is greater than maxBtSize

        -   mttDepth is greater than or equal to maxMttDepth

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 16

        -   

        -   treeType is equal to DUAL_TREE_CHROMA and modeType is equal            to MODE_TYPE_INTRA            . . .

6.4.3 Allowed Ternary Split Process

The variable allowTtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowTtSplit is set equal to FALSE:        -   cb Size is less than or equal to 2*MinTtSizeY

        -   cbWidth is greater than Min(MaxTbSizeY, maxTtSize)

        -   cbHeight is greater than Min(MaxTbSizeY, maxTtSize)

        -   mttDepth is greater than or equal to maxMttDepth

        -   x0+cbWidth is greater than pic_width_in_luma_samples

        -   y0+cbHeight is greater than pic_height_in_luma_samples

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 32

        -   

        -   treeType is equal to DUAL_TREE_CHROMA and modeType is equal            to MODE_TYPE_INTRA    -   Otherwise, allowTtSplit is set equal to TRUE.

5.8 An Example Embodiment #8

The embodiment below is about enabling MODE_IBC for SCIPU chroma blocks.

7.3.8.5 Coding Unit Syntax

coding_unit( x0, y0, cbWidth, cbHeight, cqtDepth, treeType, modeType ) {Descriptor  chType = treeType = = DUAL_TREE_CHROMA? 1 : 0  if(slice_type != I ∥ sps_ibc_enabled_flag ∥  sps_palette_enabled_flag) {  if( treeType != DUAL_TREE_CHROMA &&    !( ( ( cbWidth = = 4 &&cbHeight = = 4 ) ∥    modeType = = MODE_TYPE_INTRA )     &&!sps_ibc_enabled_flag ) )    cu_skip_flag[ x0 ][ y0 ]   if(cu_skip_flag[ x0 ][ y0 ] = = 0 && slice_type != I ae(v)    && !( cbWidth= = 4 && cbHeight = = 4 ) &&    modeType = = MODE_TYPE_ALL )   pred_mode_flag   if( ( ( slice_type = = I && cu_skip_flag ae(v)   [x0 ][ y0 ] = =0 ) ∥     ( slice_type != I && ( CuPredMode     [ chType][ x0 ][ y0 ] != MODE_INTRA ∥       

        

 ∥      ( cbWidth = = 4 && cbHeight = = 4 &&      cu_skip_flag[ x0 ][ y0] = = 0 ) ) ) ) &&    cbWidth <= 64 && cbHeight <=    64 && modeType !=MODE_TYPE_INTER &&    sps_ibc_enabled_flag &&    

 ==

 [[treeType != DUAL_TREE_CHROMA]])    pred_mode_ibc_flag ae(v)

5.9 An Example Embodiment #9 on Disallowing Block Partition whenmodeType is MODE_TYPE_INTER (Solution 1) 6.4.2 Allowed Binary SplitProcess

The variable allowBtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowBtSplit is set equal to FALSE:        -   cbSize is less than or equal to MinBtSizeY        -   cbWidth is greater than maxBtSize        -   cbHeight is greater than maxBtSize        -   mttDepth is greater than or equal to maxMttDepth        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 16        -   modeType is equal to MODE_TYPE_INTER and cbWidth*cbHeight is            less than or equal to 32        -   treeType is equal to DUAL_TREE_CHROMA and modeType is equal            to MODE_TYPE_INTRA            . . .

6.4.3 Allowed Ternary Split Process

The variable allowTtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowTtSplit is set equal to FALSE:        -   cbSize is less than or equal to 2*MinTtSizeY        -   cbWidth is greater than Min(MaxTbSizeY, maxTtSize)        -   cbHeight is greater than Min(MaxTbSizeY, maxTtSize)        -   mttDepth is greater than or equal to maxMttDepth        -   x0+cbWidth is greater than pic_width_in_luma_samples        -   y0+cbHeight is greater than pic_height_in_luma_samples        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 32        -   modeType is equal to MODE_TYPE_INTER and cbWidth*cbHeight is            less than or equal to 64        -   treeType is equal to DUAL_TREE_CHROMA and modeType is equal            to MODE_TYPE_INTRA    -   Otherwise, allowTtSplit is set equal to TRUE.

5.10 An Example Embodiment #10 on Disallowing Block Partition whenmodeType is MODE_TYPE_INTER (Solution 2) 6.4.2 Allowed Binary SplitProcess

The variable allowBtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowBtSplit is set equal to FALSE:        -   cbSize is less than or equal to MinBtSizeY

        -   cbWidth is greater than maxBtSize

        -   cbHeight is greater than maxBtSize

        -   mttDepth is greater than or equal to maxMttDepth

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 16

        -   

        -   treeType is equal to DUAL_TREE_CHROMA and modeType is equal            to MODE_TYPE_INTRA            . . .

6.4.3 Allowed Ternary Split Process

The variable allowTtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowTtSplit is set equal to FALSE:        -   cbSize is less than or equal to 2*MinTtSizeY

        -   cbWidth is greater than Min(MaxTbSizeY, maxTtSize)

        -   cbHeight is greater than Min(MaxTbSizeY, maxTtSize)

        -   mttDepth is greater than or equal to maxMttDepth

        -   x0+cbWidth is greater than pic_width_in_luma_samples

        -   y0+cbHeight is greater than pic_height_in_luma_samples

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 32

        -   

        -   treeType is equal to DUAL_TREE_CHROMA and modeType is equal            to MODE_TYPE_INTRA    -   Otherwise, allowTtSplit is set equal to TRUE.

5.11 An Example Embodiment #11

The embodiment below is about the constraints further splitting of acoding tree when MODE_TYPE_INTER is derived.

7.3.8.4 Coding Tree Syntax

coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, qgOnC,    cbSubdiv,cqtDepth, mttDepth, depthOffset,    partIdx, treeTypeCurr, modeTypeCurr) { Descriptor ...  treeType = ( modeType = = MODE_TYPE_INTRA ) ? DUAL_TREE_LUMA : treeTypeCurr  

 

  

 

 if( !split_qt_flag ) { ...

5.12 An Example Embodiment #12

The embodiment below is about the constraints on small block partitionsand prediction modes are not applied when palette mode is enabled.

7.4.9.4 Coding Tree Semantics

The variable modeTypeCondition is derived as follows:

-   -   If one of the following conditions is true, modeTypeCondition is        set equal to 0        -   slice_type==I and qtbtt_dual_tree_intra_flag is equal to 1

        -   modeTypeCurr is not equal to MODE_TYPE_ALL

        -       -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1        -   cbWidth*cbHeight is equal to 64 and split_qt_flag is equal            to 1        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER        -   cbWidth*cbHeight is equal to 32 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1+(slice_type!=I? 1:0)        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER        -   cbWidth*cbHeight is equal to 128 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER    -   Otherwise, modeTypeCondition is set equal to 0

5.13 An Example Embodiment #13

The embodiment below is ab out the small chroma intro block constraintsfor 4:2:2 color formats.

7.4.9.4 Coding Tree Semantics

The variable modeTypeCondition is derived as follows:

-   -   If one of the following conditions is true, modeTypeCondition is        set equal to 0        -   slice_type==I and qtbtt_dual_tree_intra_flag is equal to 1        -   modeTypeCurr is not equal to MODE_TYPE_ALL    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1        -   cbWidth*cbHeight is equal to 64 and split_qt_flag is equal            to 1        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER        -   cbWidth*cbHeight is equal to 32 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER    -   Otherwise, if        one of the following conditions is true, modeTypeCondition is        set equal to 1+(slice_type!=I? 1:0)        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER        -   cbWidth*cbHeight is equal to 128 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER    -   Otherwise, modeTypeCondition is set equal to 0

5.14 Example #1 of Delta QP Signaling in SCIPU

coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, qgOnC,      cbSubdiv,cqtDepth, mttDepth, depthOffset,      partIdx, treeTypeCurr,modeTypeCurr ) { Descriptor  if( ( allowSplitBtVer ∥ allowSplitBtHor ∥allowSplitTtVer ∥  allowSplitTtHor ∥ allowSplitQT )    &&( x0 + cbWidth<= pic_width_in_luma_samples )    && (y0 + cbHeight <=pic_height_in_luma_samples ))   split_cu_flag ae(v)  if(cu_qp_delta_enabled_flag && qgOnY &&  cbSubdiv <= cu_qp_delta_subdiv ) {  IsCuQpDeltaCoded = 0   CuQpDeltaVal = 0   CuQgTopLeftX = x0  CuQgTopLeftY = y0  }  if( cu_chroma_qp_offset_enabled_flag && qgOnC &&  cbSubdiv <= cu_chroma_qp_offset_subdiv )   IsCuChromaQpOffsetCoded = 0 if( split_cu_flag ) {   if( ( allowSplitBtVer ∥ allowSplitBtHor ∥  allowSplitTtVer ∥     allowSplitTtHor ) && allowSplitQT )   split_qt_flag ae(v)   if( !split_qt_flag ) {    if( ( allowSplitBtHor∥ allowSplitTtHor ) &&     ( allowSplitBtVer ∥ allowSplitTtVer ) )    mtt_split_cu_vertical_flag ae(v)    if( ( allowSplitBtVer &&allowSplitTtVer &&    mtt_split_cu_vertical_flag ) ∥     (allowSplitBtHor && allowSplitTtHor &&     !mtt_split_cu_vertical_flag))    mtt_split_cu_binary_flag ae(v)   }   if( modeTypeCondition = = 1 )   modeType = MODE_TYPE_INTRA   else if( modeTypeCondition = = 2 ) {   mode_constraint_flag ae(v)    modeType = mode_constraint_flag ?   MODE_TYPE_INTRA : MODE_TYPE_INTER   } else {    modeType =modeTypeCurr   }   treeType = ( modeType = = MODE_TYPE_INTRA ) ?  DUAL_TREE_LUMA : treeTypeCurr   if( !split_qt_flag ) {    if(MttSplitMode[ x0 ][ y0 ][ mttDepth ] = =    SPLIT_BT_VER ) {    depthOffset += ( x0 + cbWidth >     pic_width_in_luma_samples ) ? 1: 0     x1 = x0 + ( cbWidth / 2 )     coding_tree( x0, y0, cbWidth / 2,    cbHeight, qgOnY, qgOnC, cbSubdiv + 1,       cqtDepth, mttDepth + 1,depthOffset,       0, treeType, modeType )     if( x1 <pic_width_in_luma_samples )     coding_tree( x1, y0, cbWidth / 2,cbHeightY,     qgOnY, qgOnC, cbSubdiv + 1,       cqtDepth, mttDepth + 1,depthOffset,       1, treeType, modeType )    } else if( MttSplitMode[x0 ][ y0 ][ mttDepth ] = =    SPLIT_BT_HOR ) {     depthOffset += ( y0 +cbHeight >     pic_height_in_luma_samples ) ? 1 : 0     y1 = y0 + (cbHeight / 2 )     coding_tree( x0, y0, cbWidth, cbHeight /     2,qgOnY, qgOnC, cbSubdiv + 1,      cqtDepth, mttDepth + 1, depthOffset,     0, treeType, modeType )     if( y1 < pic_height_in_luma_samples )    coding_tree( x0, y1, cbWidth, cbHeight /     2, qgOnY, qgOnC,cbSubdiv + 1,       cqtDepth, mttDepth + 1, depthOffset,       1,treeType, modeType )    } else if( MttSplitMode[ x0 ][ y0 ][ mttDepth ]= =    SPLIT_TT_VER ) {     x1 = x0 + ( cbWidth / 4 )     x2 = x0 + (3 * cbWidth / 4 )     

= qgOnY && ( cbSubdiv +     2 <= cu_qp_delta_subdiv )     qgOnCnext=qgOnC && ( cbSubdiv +     2 <= cu_chroma_qp_offset_subdiv )    coding_tree( x0, y0, cbWidth / 4, cbHeight,     

 cbSubdiv + 2,      cqtDepth, mttDepth + 1, depthOffset,      0,treeType, modeType )     coding_tree( x1, y0, cbWidth / 2, cbHeight,    

 cbSubdiv + 1,      cqtDepth, mttDepth + 1, depthOffset,      1,treeType, modeType )     coding_tree( x2, y0, cbWidth / 4, cbHeight,    

 cbSubdiv + 2,      cqtDepth, mttDepth + 1, depthOffset,      2,treeType, modeType )    } else { /* SPLIT_TT_HOR */     y1 = y0 + (cbHeight / 4 )     y2 = y0 + ( 3 * cbHeight / 4 )     

= qgOnY && ( cbSubdiv +     2 <= cu_qp_delta_subdiv )     qgOnCnext=qgOnC && ( cbSubdiv + 2 <=     cu_chroma_qp_offset_subdiv )    coding_tree( x0, y0, cbWidth / 4, cbHeight,     

 cbSubdiv + 2,      cqtDepth, mttDepth + 1, depthOffset,      0,treeType, modeType )     coding_tree( x0, y1, cbWidth / 2, cbHeight,    

 cbSubdiv + 1,      cqtDepth, mttDepth + 1, depthOffset,      1,treeType, modeType )     coding_tree( x0, y2, cbWidth / 4, cbHeight,    

 cbSubdiv + 2,      cqtDepth, mttDepth + 1, depthOffset,      2,treeType, modeType )    }   } else {    x1 = x0 + ( cbWidth / 2 )    y1= y0 + ( cbHeight / 2 )    coding_tree( x0, y0, cbWidth / 2, cbHeight /   2, qgOnY, qgOnC, cbSubdiv + 2,      cqtDepth + 1, 0, 0, 0, treeType,modeType )    if( x1 < pic_width_in_luma_samples )     coding_tree( x1,y0, cbWidth / 2, cbHeight /     2, qgOnY, qgOnC, cbSubdiv + 2,     cqtDepth + 1, 0, 0, 1, treeType, modeType )    if( y1 <pic_height_in_luma_samples )     coding_tree( x0, y1, cbWidth / 2,cbHeight /     2, qgOnY, qgOnC, cbSubdiv + 2,      cqtDepth + 1, 0, 0,2, treeType, modeType )    if( y1 < pic_height_in_luma_samples &&    x1<pic_width_in_luma_samples )     coding_tree( x1, y1, cbWidth / 2,cbHeight /     2, qgOnY, qgOnC, cbSubdiv + 2,      cqtDepth + 1, 0, 0,3, treeType, modeType )   }   if( modeTypeCur = = MODE_TYPE_ALL &&  modeType = = MODE_TYPE_INTRA ) {    coding_tree( x0, y0, cbWidth,cbHeight, qgOnY,    qgOnC, cbSubdiv, cqtDepth, mttDepth, 0, 0     DUAL_TREE_CHROMA, modeType )   }  } else   coding_unit( x0, y0,cbWidth, cbHeight,   cqtDepth, treeTypeCurr, modeTypeCurr ) }

5.15 Example #2 of Delta QP Signaling in SCIPU

coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, qgOnC,      cbSubdiv,cqtDepth, mttDepth, depthOffset,      partIdx, treeTypeCurr,modeTypeCurr ) { Descriptor  if( ( allowSplitBtVer ∥ allowSplitBtHor ∥ allowSplitTtVer ∥ allowSplitTtHor ∥ allowSplitQT )    &&( x0 + cbWidth<= pic_width_in_luma_samples )    && (y0 + cbHeight <=pic_height_in_luma_samples ))   split_cu_flag ae(v)  if(cu_qp_delta_enabled_flag && qgOnY &&  cbSubdiv <= cu_qp_delta_subdiv ) {  IsCuQpDeltaCoded = 0   CuQpDeltaVal = 0   CuQgTopLeftX = x0  CuQgTopLeftY = y0  }  if( cu_chroma_qp_offset_enabled_flag && qgOnC &&  cbSubdiv <= cu_chroma_qp_offset_subdiv )   IsCuChromaQpOffsetCoded = 0 if( split_cu_flag ) {    if( ( allowSplitBtVer ∥ allowSplitBtHor ∥    allowSplitTtVer ∥ allowSplitTtHor ) &&     allowSplitQT)  split_qt_flag ae(v)   if( !split_qt_flag ) {   if( ( allowSplitBtHor ∥allowSplitTtHor ) &&     ( allowSplitBtVer ∥ allowSplitTtVer) )    mtt_split_cu_vertical_flag ae(v)   if( ( allowSplitBtVer &&allowSplitTtVer &&   mtt_split_cu_vertical_flag ) ∥     (allowSplitBtHor && allowSplitTtHor &&     !mtt_split_cu_vertical_flag))    mtt_split_cu_binary_flag ae(v)   }   if( modeTypeCondition = = 1 )   modeType = MODE_TYPE_INTRA   else if( modeTypeCondition = = 2 ) {   mode_constraint_flag ae(v)    modeType = mode_constraint_flag ?   MODE_TYPE_INTRA : MODE_TYPE_INTER   } else {    modeType =modeTypeCurr   }   treeType = ( modeType = = MODE_TYPE_INTRA ) ?  DUAL_TREE_LUMA : treeTypeCurr   if( !split_qt_flag ) {    if(MttSplitMode[ x0 ][ y0 ][ mttDepth ] = =    SPLIT_BT_VER ) {    depthOffset += ( x0 + cbWidth >     pic_width_in_luma_samples ) ? 1: 0     x1 = x0 + ( cbWidth / 2 )     coding_tree( x0, y0, cbWidth / 2,    cbHeight, qgOnY, qgOnC, cbSubdiv + 1,        cqtDepth, mttDepth + 1,depthOffset,        0, treeType, modeType )     if( x1 <pic_width_in_luma_samples )     coding_tree( x1, y0, cbWidth / 2,cbHeightY,     qgOnY, qgOnC, cbSubdiv + 1,        cqtDepth, mttDepth +1, depthOffset,        1, treeType, modeType )    } else if(MttSplitMode[ x0 ][ y0 ][ mttDepth ] = =    SPLIT_BT_HOR ) {    depthOffset += ( y0 + cbHeight >     pic_height_in_luma_samples ) ?1 : 0     y1 = y0 + ( cbHeight / 2 )     coding_tree( x0, y0, cbWidth,cbHeight /     2, qgOnY, qgOnC, cbSubdiv + 1,       cqtDepth, mttDepth +1, depthOffset,       0, treeType, modeType )     if( y1 <pic_height_in_luma_samples )     coding_tree( x0, y1, cbWidth, cbHeight/     2, qgOnY, qgOnC, cbSubdiv + 1,        cqtDepth, mttDepth + 1,depthOffset,        1, treeType, modeType )    } else if( MttSplitMode[x0 ][ y0 ][ mttDepth ] = =    SPLIT_TT_VER ) {     x1 = x0 + ( cbWidth /4 )     x2 = x0 + ( 3 * cbWidth / 4 )     

= qgOnY && ( cbSubdiv +     2 <= cu_qp_delta_subdiv )     qgOnCnext=qgOnC && ( cbSubdiv +     2 <= cu_chroma_qp_offset_subdiv )    coding_tree( x0, y0, cbWidth / 4, cbHeight,     

 cbSubdiv + 2,       cqtDepth, mttDepth + 1, depthOffset,       0,treeType, modeType )     coding_tree( x1, y0, cbWidth / 2, cbHeight,    

 cbSubdiv + 1,       cqtDepth, mttDepth + 1, depthOffset,       1,treeType, modeType )     coding_tree( x2, y0, cbWidth / 4, cbHeight,    

 cbSubdiv + 2,       cqtDepth, mttDepth + 1, depthOffset,       2,treeType, modeType )    } else { /* SPLIT_TT_HOR */     y1 = y0 + (cbHeight / 4 )     y2 = y0 + ( 3 * cbHeight / 4 )     

= qgOnY && ( cbSubdiv +     2 <= cu_qp_delta_subdiv )     qgOnCnext=qgOnC && ( cbSubdiv +     2 <= cu_chroma_qp_offset_subdiv )    coding_tree( x0, y0, cbWidth / 4, cbHeight,     

 cbSubdiv + 2,       cqtDepth, mttDepth + 1, depthOffset,       0,treeType, modeType )     coding_tree( x0, y1, cbWidth / 2, cbHeight,    

 cbSubdiv + 1,       cqtDepth, mttDepth + 1, depthOffset,       1,treeType, modeType )     coding_tree( x0, y2, cbWidth / 4, cbHeight,    

 cbSubdiv + 2,       cqtDepth, mttDepth + 1, depthOffset,       2,treeType, modeType )    }   } else {   x1 = x0 + ( cbWidth / 2 )   y1 =y0 + ( cbHeight / 2 )   coding_tree( x0, y0, cbWidth / 2, cbHeight / 2,  qgOnY, qgOnC, cbSubdiv + 2,       cqtDepth + 1, 0, 0, 0, treeType,modeType )   if( x1 < pic_width_in_luma_samples )     coding_tree( x1,y0, cbWidth / 2, cbHeight /     2, qgOnY, qgOnC, cbSubdiv + 2,      cqtDepth + 1, 0, 0, 1, treeType, modeType )   if( y1 <pic_height_in_luma_samples )     coding_tree( x0, y1, cbWidth / 2,cbHeight /     2, qgOnY, qgOnC, cbSubdiv + 2,       cqtDepth + 1, 0, 0,2, treeType, modeType )   if( y1 < pic_height_in_luma_samples &&   x1<pic_width_in_luma_samples )    coding_tree( x1, y1, cbWidth / 2,cbHeight /    2, qgOnY, qgOnC, cbSubdiv + 2,       cqtDepth + 1, 0, 0,3, treeType, modeType )   }   if( modeTypeCur = = MODE_TYPE_ALL &&  modeType = = MODE_TYPE_INTRA ) {   coding_tree( x0, y0, cbWidth,cbHeight, qgOnY, 0,   cbSubdiv, cqtDepth, mttDepth, 0, 0      DUAL_TREE_CHROMA, modeType )   }  } else   coding_unit( x0, y0,cbWidth, cbHeight, cqtDepth,   treeTypeCurr, modeTypeCurr ) }

5.16 Example #3 of Delta QP Signaling in SCIPU

coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, qgOnC,      cbSubdiv,cqtDepth, mttDepth, depthOffset,      partIdx, treeTypeCurr,modeTypeCurr ) { Descriptor  if( ( allowSplitBtVer ∥ allowSplitBtHor ∥ allowSplitTtVer ∥ allowSplitTtHor ∥ allowSplitQT )    &&( x0 + cbWidth<= pic_width_in_luma_samples )    && (y0 + cbHeight <=pic_height_in_luma_samples ))   split_cu_flag ae(v)  

 

  IsCuQpDeltaCoded = 0   CuQpDeltaVal = 0   CuQgTopLeftX = x0  CuQgTopLeftY = y0  }  if( cu_chroma_qp_offset_enabled_flag && qgOnC &&  cbSubdiv <= cu_chroma_qp_offset_subdiv &&   

 )   IsCuChromaQpOffsetCoded = 0  if( split_cu_flag ) {   if( (allowSplitBtVer ∥ allowSplitBtHor ∥   allowSplitTtVer ∥    allowSplitTtHor ) && allowSplitQT )   split_qt_flag ae(v)   if(!split_qt_flag ) {   if( ( allowSplitBtHor ∥ allowSplitTtHor ) &&     (allowSplitBtVer ∥ allowSplitTtVer ) )     mtt_split_cu_vertical_flagae(v)   if( ( allowSplitBtVer && allowSplitTtVer &&  mtt_split_cu_vertical_flag ) ∥     ( allowSplitBtHor &&allowSplitTtHor &&     !mtt_split_cu_vertical_flag))    mtt_split_cu_binary_flag ae(v)   }   if( modeTypeCondition = = 1 )   modeType = MODE_TYPE_INTRA   else if( modeTypeCondition = = 2 ) {   mode_constraint_flag ae(v)    modeType = mode_constraint_flag ?   MODE_TYPE_INTRA : MODE_TYPE_INTER   } else {    modeType =modeTypeCurr   }   treeType = ( modeType = = MODE_TYPE_INTRA ) ?  DUAL_TREE_LUMA : treeTypeCurr   if( !split_qt_flag ) {    if(MttSplitMode[ x0 ][ y0 ][ mttDepth ] = =    SPLIT_BT_VER ) {    depthOffset += ( x0 + cbWidth >     pic_width_in_luma_samples ) ? 1: 0     x1 = x0 + ( cbWidth / 2 )     coding_tree( x0, y0, cbWidth / 2,    cbHeight, qgOnY, qgOnC,        cbSubdiv + 1, cqtDepth, mttDepth +       1, depthOffset, 0, treeType, modeType )     if( x1 <pic_width_in_luma_samples )     coding_tree( x1, y0, cbWidth / 2,    cbHeightY, qgOnY, qgOnC,        cbSubdiv + 1, cqtDepth, mttDepth +       1, depthOffset, 1, treeType, modeType )    } else if(MttSplitMode[ x0 ][ y0 ][ mttDepth ] = =    SPLIT_BT_HOR ) {    depthOffset += ( y0 + cbHeight >     pic_height_in_luma_samples ) ?1 : 0     y1 = y0 + ( cbHeight / 2 )     coding_tree( x0, y0, cbWidth,    cbHeight / 2, qgOnY,     qgOnC, cbSubdiv + 1, cqtDepth, mttDepth +      1, depthOffset, 0, treeType, modeType )     if( y1 <pic_height_in_luma_samples )     coding_tree( x0, y1, cbWidth,    cbHeight / 2, qgOnY,     qgOnC, cbSubdiv + 1, cqtDepth, mttDepth +       1, depthOffset, 1, treeType, modeType )    } else if(MttSplitMode[ x0 ][ y0 ][ mttDepth ] = =    SPLIT_TT_VER ) {     x1 =x0 + ( cbWidth / 4 )     x2 = x0 + ( 3 * cbWidth / 4 )     

= qgOnY && ( cbSubdiv + 2 <=     cu_qp_delta_subdiv )     qgOnCnext=qgOnC && ( cbSubdiv + 2 <=     cu_chroma_qp_offset_subdiv )    coding_tree( x0, y0, cbWidth / 4, cbHeight,       

 cbSubdiv + 2,       cqtDepth, mttDepth +       1, depthOffset, 0,treeType, modeType )     coding_tree( x1, y0, cbWidth / 2, cbHeight,      

 cbSubdiv + 1,       cqtDepth, mttDepth +       1, depthOffset, 1,treeType, modeType )     coding_tree( x2, y0, cbWidth / 4, cbHeight,      

 cbSubdiv + 2,       cqtDepth, mttDepth +       1, depthOffset, 2,treeType, modeType )    } else { /* SPLIT_TT_HOR */     y1 = y0 + (cbHeight / 4 )     y2 = y0 + ( 3 * cbHeight / 4 )     

= qgOnY && ( cbSubdiv + 2 <=     cu_qp_delta_subdiv )     qgOnCnext=qgOnC && ( cbSubdiv +     2 <= cu_chroma_qp_offset_subdiv )    coding_tree( x0, y0, cbWidth, cbHeight / 4       

 cbSubdiv +       2, cqtDepth,       mttDepth + 1, depthOffset, 0,      treeType, modeType )     coding_tree( x0, y1, cbWidth, cbHeight /2       

 cbSubdiv +       1, cqtDepth, mttDepth +       1, depthOffset, 1,treeType, modeType )     coding_tree( x0, y2, cbWidth, cbHeight /       4,

 cbSubdiv +       2, cqtDepth, mttDepth +       1, depthOffset, 2,treeType, modeType )    }   } else {    x1 = x0 + ( cbWidth / 2 )    y1= y0 + ( cbHeight / 2 )    coding_tree( x0, y0, cbWidth / 2, cbHeight /2,       qgOnY, qgOnC, cbSubdiv + 2, cqtDepth +       1, 0, 0, 0,treeType, modeType )    if( x1 < pic_width_in_luma_samples )    coding_tree( x1, y0, cbWidth / 2, cbHeight / 2,       qgOnY, qgOnC,cbSubdiv + 2, cqtDepth +       1, 0, 0, 1, treeType, modeType )    if(y1 < pic_height_in_luma_samples )     coding_tree( x0, y1, cbWidth / 2,cbHeight / 2,       qgOnY, qgOnC, cbSubdiv + 2, cqtDepth +       1, 0,0, 2, treeType, modeType )    if( y1 < pic_height_in_luma_samples &&   x1 <pic_width_in_luma_samples )     coding_tree( x1, y1, cbWidth / 2,cbHeight / 2,       qgOnY, qgOnC, cbSubdiv + 2, cqtDepth +       1, 0,0, 3, treeType, modeType )   }   if( modeTypeCur = = MODE_TYPE_ALL &&  modeType = = MODE_TYPE_INTRA ) {    coding_tree( x0, y0, cbWidth,cbHeight, qgOnY,    0, cbSubdiv, cqtDepth, mttDepth, 0, 0      DUAL_TREE_CHROMA, modeType )   }  } else   coding_unit( x0, y0,cbWidth, cbHeight, cqtDepth,   treeTypeCurr, modeTypeCurr ) }

5.17 Example #4 of Delta QP Signaling in SCIPU

coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, qgOnC,      cbSubdiv,cqtDepth, mttDepth, depthOffset,      partIdx, treeTypeCurr,modeTypeCurr ) { Descriptor  if( ( allowSplitBtVer ∥ allowSplitBtHor ∥allowSplitTtVer ∥  allowSplitTtHor ∥ allowSplitQT )    &&( x0 + cbWidth<= pic_width_in_luma_samples )    && (y0 + cbHeight <=pic_height_in_luma_samples ))   split_cu_flag ae(v)  if(cu_qp_delta_enabled_flag && qgOnY &&  cbSubdiv <= cu_qp_delta_subdiv ) {  IsCuQpDeltaCoded = 0   CuQpDeltaVal = 0   CuQgTopLeftX = x0  CuQgTopLeftY = y0  }  if( cu_chroma_qp_offset_enabled_flag && qgOnC &&  cbSubdiv <= cu_chroma_qp_offset_subdiv )   IsCuChromaQpOffsetCoded = 0 if( split_cu_flag ) {   if( ( allowSplitBtVer ∥ allowSplitBtHor ∥  allowSplitTtVer ∥     allowSplitTtHor ) && allowSplitQT )  split_qt_flag ae(v)   if( !split_qt_flag ) {   if( ( allowSplitBtHor ∥allowSplitTtHor ) &&     ( allowSplitBtVer ∥ allowSplitTtVer ) )    mtt_split_cu_vertical_flag ae(v)   if( ( allowSplitBtVer &&allowSplitTtVer &&   mtt_split_cu_vertical_flag ) ∥     (allowSplitBtHor && allowSplitTtHor &&     !mtt_split_cu_vertical_flag))    mtt_split_cu_binary_flag ae(v)   }   if( modeTypeCondition = = 1 )   modeType = MODE_TYPE_INTRA   else if( modeTypeCondition = = 2 ) {   mode_constraint_flag ae(v)    modeType = mode_constraint_flag ?   MODE_TYPE_INTRA : MODE_TYPE_INTER   } else {    modeType =modeTypeCurr   }   

    

  treeType = ( modeType = = MODE_TYPE_INTRA ) ?   DUAL_TREE_LUMA :treeTypeCurr   if( !split_qt_flag ) {    if( MttSplitMode[ x0 ][ y0 ][mttDepth ] = =    SPLIT_BT_VER ) {     depthOffset += ( x0 + cbWidth >    pic_width_in_luma_samples ) ? 1 : 0     x1 = x0 + ( cbWidth / 2 )    coding_tree( x0, y0, cbWidth / 2, cbHeight,     qgOnY, qgOnC,cbSubdiv + 1,        cqtDepth, mttDepth + 1, depthOffset,        0,treeType, modeType )     if( x1 < pic_width_in_luma_samples )    coding_tree( x1, y0, cbWidth / 2, cbHeight,     qgOnY, qgOnC,cbSubdiv + 1,        cqtDepth, mttDepth + 1, depthOffset, 1,       treeType, modeType )    } else if( MttSplitMode[ x0 ][ y0 ][mttDepth ] = =    SPLIT_BT_HOR ) {     depthOffset += ( y0 + cbHeight >    pic_height_in_luma_samples ) ? 1 : 0     y1 = y0 + ( cbHeight / 2 )    coding_tree( x0, y0, cbWidth, cbHeight / 2,     qgOnY, qgOnC,cbSubdiv + 1,       cqtDepth, mttDepth + 1, depthOffset,       0,treeType, modeType )     if( y1 < pic_height_in_luma_samples )    coding_tree( x0, y1, cbWidth, cbHeight / 2,     qgOnY, qgOnC,cbSubdiv + 1,        cqtDepth, mttDepth + 1, depthOffset,        1,treeType, modeType )    } else if( MttSplitMode[ x0 ][ y0 ][ mttDepth ]= =    SPLIT_TT_VER ) {     x1 = x0 + ( cbWidth / 4 )     x2 = x0 + (3 * cbWidth / 4 )     qgOnY = qgOnY && ( cbSubdiv + 2 <=    cu_qp_delta_subdiv )     qgOnC = qgOnC && ( cbSubdiv + 2 <=    cu_chroma qp_offset_subdiv )     coding_tree( x0, y0, cbWidth / 4,cbHeight,     qgOnY, qgOnC, cbSubdiv + 2,       cqtDepth, mttDepth + 1,depthOffset, 0,       treeType, modeType )     coding_tree( x1, y0,cbWidth / 2, cbHeight,     qgOnY, qgOnC, cbSubdiv + 1,       cqtDepth,mttDepth + 1, depthOffset, 1,       treeType, modeType )    coding_tree( x2, y0, cbWidth / 4, cbHeight,     qgOnY, qgOnC,cbSubdiv + 2,       cqtDepth, mttDepth + 1, depthOffset, 2,      treeType, modeType )    } else { /* SPLIT_TT_HOR */     y1 = y0 +( cbHeight / 4 )     y2 = y0 + ( 3 * cbHeight / 4 )     qgOnY = qgOnY &&( cbSubdiv + 2 <=     cu_qp_delta_subdiv )     qgOnC = qgOnC && (cbSubdiv + 2 <=     cu_chroma_qp_offset_subdiv )     coding_tree( x0,y0, cbWidth, cbHeight / 4,     qgOnY, qgOnC, cbSubdiv + 2,      cqtDepth, mttDepth + 1, depthOffset, 0,       treeType, modeType )    coding_tree( x0, y1, cbWidth, cbHeight / 2,     qgOnY, qgOnC,cbSubdiv + 1,       cqtDepth, mttDepth + 1, depthOffset, 1,      treeType, modeType )     coding_tree( x0, y2, cbWidth, cbHeight /4,     qgOnY, qgOnC, cbSubdiv + 2,       cqtDepth, mttDepth + 1,depthOffset, 2,       treeType, modeType )    }   } else {   x1 = x0 + (cbWidth / 2 )   y1 = y0 + ( cbHeight / 2 )   coding_tree( x0, y0,cbWidth / 2, cbHeight / 2, qgOnY,       qgOnC, cbSubdiv + 2, cqtDepth +1, 0, 0, 0,       treeType, modeType )   if( x1 <pic_width_in_luma_samples )     coding_tree( x1, y0, cbWidth / 2,cbHeight / 2,     qgOnY, qgOnC,       cbSubdiv + 2, cqtDepth + 1, 0, 0,1,       treeType, modeType )   if( y1 < pic_height_in_luma_samples )    coding_tree( x0, y1, cbWidth / 2, cbHeight / 2,     qgOnY, qgOnC,      cbSubdiv + 2, cqtDepth + 1, 0, 0, 2,       treeType, modeType )  if( y1 < pic_height_in_luma_samples &&   x1 <pic_width_in_luma_samples)     coding_tree( x1, y1, cbWidth / 2, cbHeight / 2,     qgOnY, qgOnC,cbSubdiv + 2,       cqtDepth + 1, 0, 0, 3, treeType, modeType )   }  if( modeTypeCur = = MODE_TYPE_ALL &&   modeType = = MODE_TYPE_INTRA ){   coding_tree( x0, y0, cbWidth, cbHeight, qgOnY,   qgOnC, cbSubdiv,cqtDepth, mttDepth, 0, 0       DUAL_TREE_CHROMA, modeType )   }  } else  coding_unit( x0, y0, cbWidth, cbHeight, cqtDepth,   treeTypeCurr,modeTypeCurr ) }

FIG. 17 is a block diagram of a video processing apparatus 1700. Theapparatus 1700 may be used to implement one or more of the methodsdescribed herein. The apparatus 1700 may be embodied in a smartphone,tablet, computer, Internet of Things (IoT) receiver, and so on. Theapparatus 1700 may include one or more processors 1702, one or morememories 1704 and video processing hardware 1706. The processor(s) 1702may be configured to implement one or more methods described in thepresent document. The memory (memories) 1704 may be used for storingdata and code used for implementing the methods and techniques describedherein. The video processing hardware 1706 may be used to implement, inhardware circuitry, some techniques described in the present document.In some embodiments, the hardware 1706 may be at least partly within theprocessor 1702, e.g., a graphics co-processor.

FIG. 18 is a flowchart for a method 1800 of processing a video. Themethod 1800 includes parsing (1802), for a conversion between a videoregion of a video and a coded representation of the video region, thecoded representation according to a syntax rule that defines arelationship between a chroma block size and a color format of the videoregion; and performing (1804) the conversion by performing the parsingaccording to the syntax rule.

Some embodiments of the disclosed technology include making a decisionor determination to enable a video processing tool or mode. In anexample, when the video processing tool or mode is enabled, the encoderwill use or implement the tool or mode in the processing of a block ofvideo, but may not necessarily modify the resulting bitstream based onthe usage of the tool or mode. That is, a conversion from the block ofvideo to the bitstream representation of the video will use the videoprocessing tool or mode when it is enabled based on the decision ordetermination. In another example, when the video processing tool ormode is enabled, the decoder will process the bitstream with theknowledge that the bitstream has been modified based on the videoprocessing tool or mode. That is, a conversion from the bitstreamrepresentation of the video to the block of video will be performedusing the video processing tool or mode that was enabled based on thedecision or determination.

Some embodiments of the disclosed technology include making a decisionor determination to disable a video processing tool or mode. In anexample, when the video processing tool or mode is disabled, the encoderwill not use the tool or mode in the conversion of the block of video tothe bitstream representation of the video. In another example, when thevideo processing tool or mode is disabled, the decoder will process thebitstream with the knowledge that the bitstream has not been modifiedusing the video processing tool or mode that was disabled based on thedecision or determination.

In the present document, the term “video processing” may refer to videoencoding, video decoding, video compression or video decompression. Forexample, video compression algorithms may be applied during conversionfrom pixel representation of a video to a corresponding bitstreamrepresentation or vice versa. The bitstream representation of a currentvideo block may, for example, correspond to bits that are eitherco-located or spread in different places within the bitstream, as isdefined by the syntax. For example, a macroblock may be encoded in termsof transformed and coded error residual values and also using bits inheaders and other fields in the bitstream.

The following first set of clauses may be implemented in someembodiments.

The following clauses may be implemented together with additionaltechniques described in item 1 of the previous section.

1. A method of video processing, comprising: parsing, for a conversionbetween a video region of a video and a coded representation of thevideo region, the coded representation according to a syntax rule thatdefines a relationship between a chroma block size and a color format ofthe video region; and performing the conversion by performing theparsing according to the syntax rule.

2. The method of clause 1, wherein the color format is 4:4:4 and wherethe syntax rule specifies that the chroma block is subject to a samesize constraint as that for a luma blocks.

3. The method of clause 1, wherein the color format is 4:2:2 and wherethe syntax rule specifies that the chroma block is subject to a samesize constraint as that for 4:2:0 color format.

4. The method of any of clauses 1-3, wherein the syntax specifies that aprediction modes and small block partitions are used in a chroma-formatdependent manner.

5. The method of clause 1, wherein the syntax rule defines that asmallest allowed size feature is enabled for the conversion of the videoregion based on the color format of the video region.

The following clauses may be implemented together with additionaltechniques described in item 2 of the previous section.

6. A method of video processing, comprising: determining, based on aproperty of a video and a chroma format of the video, a coding mode of acoding tree node of the video; and performing a conversion between acoded representation of the video and a video block of the coding treenode using the determined coding mode.

7. The method of clause 6, wherein the coding mode is determined to beMODE_TYPE_ALL for the chroma format being 4:2:2, MODE_TYPE_INTRA orMODE_TYPE_INTER for the chroma format being 4:2:0 in case the propertyis:

i. the coding node is an M×N coding tree node with a horizontal binarytree split;

ii. the coding node is an M×N coding tree node with a vertical binarytree split;

iii. the coding node is an M×N coding tree node with a horizontalternary tree split; or

iv. the coding node is an M×N coding tree node with a vertical ternarytree split.

8. The method of clause 7, wherein M=8, or 16 or 32 and N=4 or 8 or 16.

The following clauses may be implemented together with additionaltechniques described in item 12 of the previous section.

9. A method of video processing, comprising: determining, based on arule, whether a certain size of chroma blocks is allowed in a videoregion of a video; and performing a conversion between the video regionand a coded representation of the video region based on the determining.

10. The method of clause 9, wherein the rule specifies that 2×N chromablocks are disallowed due to the video region including a dual treepartition.

11. The method of clause 9, wherein the rule specifies that 2N chromablocks are disallowed due to the video region including a single treepartition.

12. The method of clauses 10 or 11, wherein N<=64.

The following clauses may be implemented together with additionaltechniques described in items 13, 14 and 15 of the previous section.

13. A method of video processing, comprising: determining, based on arule that allows use of a coding mode for a video condition, that acoding mode is permitted for a video region; and performing a conversionbetween a coded representation of pixels in the video region and pixelsof the video region based on the determining.

14. The method of clause 13, wherein the video condition is block size,and wherein the rule allows use of intra block copy mode for small blocksizes of luma blocks.

15. The method of clause 14, wherein the small block sizes include 8×4,8×8, 16×4 or 4×N luma block sizes.

16. The method of clause 13, wherein the rule allows use of intra blockcopy mode for conversion of the video region using a MODE_TYPE_INTERmode of coding.

17. The method of clause 13, wherein the rule allows use of palettecoding mode for conversion of the video region using a MODE_TYPE_INTERmode of coding.

The following clauses may be implemented together with additionaltechniques described in items 16, 17, 18 of the previous section.

18. A method of video processing, comprising: performing a conversionbetween a video block of a video and a coded representation of the videoblock using a video coding mode, wherein a syntax element signaling thecoding mode is selectively included in the coded representation based ona rule.

19. The method of clause 18, wherein the video coding mode is an intrablock coding mode and wherein the rule specifies to use a type of thevideo coding mode to control inclusion of the syntax element in thecoded representation.

20. The method of clause 19, wherein the rule specifies explicitlysignaling a non-SKIP block.

21. The method of clause 18, wherein the rule specifies to implicitlysignal intra block copy flag based on a skip flag and a mode type of thevideo block.

22. The method of clause 18, wherein the coding mode is a palette codingmode and wherein the rule specifies to selectively include a palettecoding indicator based on mode type of the video block.

The following clauses may be implemented together with additionaltechniques described in item 21 of the previous section.

23. A method of video processing, comprising: determining, due to achroma block having a size less than a threshold size, that a transformtype used during a conversion between the chroma block and a codedrepresentation of the chroma block is different from a transform typeused for a corresponding luma block conversion; and performing theconversion based on the determining.

24. The method of clause 23, wherein the threshold size is M×N, whereinM is 2.

The following clauses may be implemented together with additionaltechniques described in item 22 of the previous section.

25. The method of any of clauses 1 to 24 wherein, the conversion uses acombined inter and intra prediction mode as a MODE_TYPE_INTRA mode.

26. The method of any of clauses 18 to 22, wherein the conversion uses acombined inter and intra prediction mode as a MODE_TYPE_INTER mode. Forexample, when considering CIIP as MODE_TYPE_INTER, methods described initem 14-17 in the previous section may be applied. Or when methodsdescribed in items 14-16 are applied, CIIP can be considered asMODE_TYPE_INTER.

The following clauses may be implemented together with additionaltechniques described in items 3-6 of the previous section.

27. A method of video processing, comprising: determining, whether asmallest chroma block rule is enforced during a conversion between acoded representation of a video region and pixel values of the videoregion, based on a coding condition of the video region; and performingthe conversion based on the determining.

28. The method of clause 27, wherein the coding condition comprises acolor format of the video region.

29. The method of clause 28, wherein the video region has a width of Mpixels and a height of N pixels, and wherein the coding conditionfurther depends on values of M and/or N.

30. The method of clause 29, wherein the smallest chroma block rule isenabled due to the video region having 4:2:2 color format and M*N=32 orM*N=64.

The following clauses may be implemented together with additionaltechniques described in items 7-11 of the previous section.

31. A method of video processing, comprising: determining, for aconversion between a coded representation of a video region in a 4:2:2format and pixel values of the video region, a mode type to be used forthe conversion based on whether a smallest chroma block rule is enabledfor the video region; and performing the conversion based on thedetermining.

32. The method of clause 31, wherein the mode type of the video regionis set to 1 due to the video region having 4:2:2 format and the smallestchroma block rule being enabled.

33. The method of clause 31, wherein the determining the mode typeincludes determining the mode type to be an INTRA type due to thesmallest chroma block rule being enabled for the video region.

34. The method of clause 31, wherein the determining the mode typeincludes determining that the mode type INTER is disabled due to thesmallest chroma block rule being enabled for the video region.

The following clauses may be implemented together with additionaltechniques described in items 7-11 of the previous section.

35. A method of video processing, comprising: determining, for aconversion between a coded representation of a video block and a videoblock of a video, whether block partitioning is allowed during theconversion, based on a mode type used during the conversion or adimension of the video block; and performing the conversion using thedetermining.

36. The method of clause 35, wherein the block portioning comprises abinary tree partitioning or a ternary tree partitioning.

37. The method of any of clauses, 35-36 wherein, in case that the modetype is INTER mode, the block partitioning is based on a restrictionrule that allows or disallows partition types.

38. The method of any of clauses 1 to 37, wherein the conversioncomprises encoding the video into the coded representation.

39. The method of any of clauses 1 to 37, wherein the conversioncomprises decoding the coded representation to generate pixel values ofthe video.

40. A video decoding apparatus comprising a processor configured toimplement a method recited in one or more of clauses 1 to 39.

41. A video encoding apparatus comprising a processor configured toimplement a method recited in one or more of clauses 1 to 39.

42. A computer program product having computer code stored thereon, thecode, when executed by a processor, causes the processor to implement amethod recited in any of clauses 1 to 39.

43. A method, apparatus or system described in the present document.

The second set of clauses describe certain features and aspects of thedisclosed techniques in the previous section (e.g., items 1, 3-11, 18,19, and 24).

1. A method of video processing (e.g., method 2110 shown in FIG. 21A),comprising: determining (2112), for a conversion between a video regionof a video and a coded representation of the video, an intra codingcharacteristic of the video region based on a color format of the videoaccording to a rule; and performing (2114) the conversion according tothe intra coding characteristic.

2. The method of clause 1, wherein the rule specifies that in case thatthe color format of the video region is 4:0:0 or 4:4:4, the intra codingcharacteristic is that all coding modes are enabled for the video regionand wherein the coded representation includes a MODE_TYPE_ALL value fora syntax element indicating a mode type used for the video region.

3. The method of clauses 1-2, wherein the rule specifies that in casethat the color format is 4:0:0 or 4:4:4, the coded representationincludes a syntax element indicative of a condition for determining amode type is set to 0.

4. The method of any of clauses 1-3, wherein the rule specifies thatwhether a restriction on a smallest allowed size for an intra codedchroma block in the video region is enabled depends on the color format.

5. The method of clause 4, wherein the rule specifies that therestriction is enabled for 4:2:0 and 4:2:2 formats.

6. The method of clause 4, wherein the rule specifies that therestriction is disabled for 4:0:0 and 4:4:4 formats.

7. A method of video processing (e.g., method 2120 shown in FIG. 21B),comprising: performing (2122) a conversion between a current video blockof a video and a coded representation of the video, wherein the codedrepresentation conforms to a format rule, and wherein the format rulespecifies a syntax element, modeType, indicative of a coding mode of thecurrent video block, that is equal to either MODE_TYPE_NO_INTER thatrestricts use of the inter coding mode for the conversion, orMODE_TYPE_NO_INTRA that restricts use of the intra mode for theconversion.

8. A method of video processing (e.g., method 2120 shown in FIG. 21B),comprising: performing (2122) a conversion between a video and a codedrepresentation of the video, wherein the coded representation conformsto a format rule that specifies that a flag indicating a prediction modeconstraint is not included in the coded representation in case that achroma format of the video is 4:2:2, 4:0:0, or 4:4:4.

9. The method of clause 8, wherein in case that the flag is not present,a corresponding value is inferred as 0 or 1.

10. A method of video processing (e.g., method 2130 shown in FIG. 21C),comprising: determining (2132), for a conversion between a video regionof a video and a coded representation of the video, whether and/or how arestriction on a size of a smallest chroma intra prediction block to thevideo region is enabled according to a rule; and performing (2134) theconversion based on the determining, wherein the rule is dependent onwhether a color format of the video is 4:2:0 or 4:2:2.

11. A method of video processing, comprising: determining, for aconversion between a video region of a video and a coded representationof the video, whether a restriction on a size of a smallest chroma intraprediction block to the video region is enabled according to a rule; andperforming the conversion based on the determining, wherein the rule isdependent on a color format of the video and/or a width (M) and a height(N) of the video region, and wherein the rule further specifies that,for the video region that is a coding tree node with a BT (binary tree)split, then the restriction on the smallest chroma intra predictionblock is disabled in case that 1) the color format of the video is 4:2:2and 2) that a multiplication of M and N is a value from a set of values,wherein the set of values includes 64.

12. The method of clause 11, wherein the rule further specifies that therestriction on the smallest chroma intra prediction block is enabled incase 1) that the color format of the video is 4:2:2 and 2) that the setof values further includes 32.

13. The method of clause 11, wherein the rule further specifies that therestriction on the smallest chroma intra prediction block is disabled incase 1) that the color format of the video is 4:2:2 and 2) that the setof values further includes 128.

14. The method of clause 11, wherein the rule further specifies, for thevideo region that is a coding tree node with a split_qt_flag equal to 1,that the restriction on the smallest chroma intra prediction block isenabled in case that the color format of the video is 4:2:2.

15. The method of clause 11, wherein the rule further specifies, for thevideo region that is a coding tree node with a TT (ternary tree) split,that the restriction on the smallest chroma intra prediction block isenabled in case that the color format of the video is 4:2:2.

16. The method of clause 11, wherein the rule further specifies, for thevideo region that is a coding tree node with a BT (binary tree) split,that the restriction on the smallest chroma intra prediction block isenabled in case that 1) the color format of the video is 4:2:2 and 2)that the set of values further includes 32.

17. The method of any of clauses 11 to 16, wherein the rule furtherspecifies, for the smallest chroma intra prediction block in the videohaving a 4:2:2 color format, a modeTypeCondition is always equal to 1.

18. The method of any of clauses 11 to 17, wherein the rule furtherspecifies, for the smallest chroma intra prediction block in the videohaving a 4:2:2 color format, only MODE_TYPE_INTRA that allows use of anintra mode, a palette mode, and an intra block copy mode for theconversion is allowed.

19. A method of video processing, comprising: performing a conversionbetween a video region of a video and a coded representation of thevideo according to a restriction on a smallest chroma intra predictionblock size, wherein the coded representation conforms to a format rulethat specifies a value of a syntax field in the coded representation,due to a 4:2:2 color format of the video.

20. The method of clause 19, wherein the syntax field corresponds to amodeTypeCondition of the SCIPU block and wherein the format rule furtherspecifies, due to the 4:2:2 color format, that the modeTypeCondition isalways 1.

21. The method of clause 19, wherein the syntax field corresponds to amodeTypeCondition of the SCIPU block and wherein the format rule furtherspecifies, due to the 4:2:2 color format, that the modeTypeCondition is0 or 1.

22. The method of clause 19, wherein the syntax field corresponds to amodeTypeCondition of the SCIPU block and wherein the format rule furtherspecifies, due to the 4:2:2 color format, that the modeTypeCondition isnot 2.

23. The method of clause 19, wherein the syntax field corresponds to amodeType of the SCIPU block and wherein the format rule furtherspecifies, due to the 4:2:2 color format, that the modeType is alwaysequal to MODE_TYPE_INTRA that allows use of an intra mode, a palettemode, and an intra block copy mode.

24. The method of clause 19, wherein the syntax field corresponds to amodeType of the SCIPU block and wherein the format rule furtherspecifies, due to the 4:2:2 color format, that the modeType is equalto 1) MODE_TYPE_ALL that allows use of an inter coding mode, an intramode, a palette mode, and an intra block copy mode for the conversion or2) MODE_TYPE_INTRA that that allows use of an intra mode, a palettemode, and an intra block copy mode.

25. The method of clause 19, wherein the syntax field corresponds to amodeType of the SCIPU block and wherein the format rule furtherspecifies, due to the 4:2:2 color format, that the modeType does notcorrespond to MODE_TYPE_INTER that allows use of an inter mode only forthe conversion.

26. A method of video processing (e.g., method 2140 shown in FIG. 21D),comprising: determining (2142), for a conversion between a current videoblock of a video and a coded representation of the video, anapplicability of a partitioning scheme to the current video blockaccording to a rule; and performing (2144) the conversion based on thedetermining.

27. The method of clause 26, wherein the rule specifies that thedetermining determines the applicability based on at least one of a modetype used during the conversion or a dimension of the current videoblock, and wherein the partitioning scheme comprises a BT (binary tree)split and/or a TT (ternary tree) split.

28. The method of clause 27, wherein in case that the mode type is equalto a MODE_TYPE_INTER that allows use of an inter mode only for theconversion, the BT split is disallowed for the current video block.

29. The method of clause 27, wherein in case that the mode type is equalto a MODE_TYPE_INTER that allows use of an inter mode only for theconversion, the TT split is disallowed for the current video block.

30. The method of clause 27, wherein in case that M*N is less than orequal to 32 and the mode type is equal to MODE_TYPE_INTER that allowsuse of an inter mode only for the conversion, the BT split isdisallowed, whereby M and N correspond to a height and a width of thecurrent video block.

31. The method of clause 27, wherein in case that M*N is less than orequal to 64 and the mode type is equal to MODE_TYPE_INTER that allowsuse of an inter mode only for the conversion, the TT split isdisallowed, whereby M and N correspond to a height and a width of thecurrent video block.

32. The method of clause 26, wherein the rule specifies to restrict acertain partitioning scheme based on a syntax element, modeTypeCurr,that is included in the coded representation and descriptive of a modetype used during the conversion, and wherein the certain partitioningscheme comprises a BT (binary tree) split, a TT (ternary tree) split,and/or QT (quaternary tree) split.

33. The method of clause 32, wherein, due to the modeTypeCurr that isequal to MODE_TYPE_INTER that allows use of an inter mode only for theconversion, the BT split is disallowed.

34. The method of clause 32, wherein, due to the modeTypeCurr that isequal to MODE_TYPE_INTER that allows use of an inter mode only for theconversion, the TT split is disallowed.

35. The method of clause 32, wherein, due to the modeTypeCurr that isequal to MODE_TYPE_INTER that allows use of an inter mode only for theconversion, the QT split is disallowed.

36. The method of clause 32, wherein the BT split is disallowed in casethat the modeTypeCurr that is equal to MODE_TYPE_INTER that allows useof an inter mode only for the conversion and that a luma block size isless than or equal to 32.

37. The method of clause 32, wherein the TT split is disallowed in casethat the modeTypeCurr that is equal to MODE_TYPE_INTER that allows useof an inter mode only for the conversion and that a luma block size isless than or equal to 64.

38. A method of video processing (e.g., method 2150 shown in FIG. 21E),comprising: determining (2152), for a conversion between a video blockof a video and a coded representation of the video, whether an intermode is enabled according to a rule, and performing (2154) theconversion based on the determining, wherein the rule specifies that theinter mode is enabled in case that a dual tree partitioning of lumasamples is enabled for the video block.

39. The method of clause 38, wherein the coded representation includes asyntax field that is equal to DUAL_TREE_LUMA.

40. The method of clause 38, wherein the coding unit coded in the intermode contains the luma samples only for color formats with multiplecolor components.

41. The method of clause 38, wherein the coded representation includes aflag indicative of a prediction mode applied to the video block and theflag is parsed for the video block corresponding to a luma block havinga dual tree type.

42. The method of clause 38, wherein the rule further specifies to applysame constraints about the inter mode regardless of whether the dualtree partitioning or a single tree partitioning of the luma samples isenabled for the video block.

43. A method of video processing (e.g., method 2160 shown in FIG. 21F),comprising: determining (2162), for a conversion between a video regionof a video and a coded representation of the video, based on a rule,whether use of a palette mode is permitted for the video region; andperforming (2164) the conversion based on the determining, wherein thepalette mode includes encoding the video region using a palette ofrepresentative sample values.

44. The method of clause 43, the rule specifies that the palette mode isallowed in case that a mode type of the video region is equal toMODE_TYPE_INTRA that allows use of an intra mode, a palette mode, and anintra block copy mode for the conversion or MODE_TYPE_INTER that allowsuse of an inter mode only for the conversion.

45. The method of clause 43, wherein the rule specifies that the palettemode is allowed independently of a mode type of the video region.

46. The method of clause 43, wherein the rule is based on a slice typeand a mode type of the video region.

47. The method of clause 46, wherein the rule specifies that the palettemode is allowed for an I slice with the mode type that is equal toMODE_TYPE_INTRA that allows use of an intra mode, a palette mode, and anintra block copy mode for the conversion.

48. The method of clause 46, wherein the rule specifies that the palettemode is allowed for a PB slice with the mode type that is equal toMODE_TYPE_INTRA that allows use of an intra mode, a palette mode, and anintra block copy mode for the conversion.

49. The method of clause 43, wherein the rule further specifies that alocal dual tree is disallowed in case that the palette mode is allowed.

50. The method of clause 43, wherein a modeTypeCondition is always set 0in case that the palette mode is enabled.

51. A method of video processing, comprising: performing a conversionbetween a current video block of a video and a coded representation ofthe video, wherein the coded representation conforms to a format rule,wherein the format rule specifies a syntax element, modeType, thatincludes a MODE_TYPE_IBC that allows use of an intra block copy mode forthe conversion or MODE_TYPE_PALETTE that allows use of a palette modefor the conversion, wherein the intra block copy mode includes encodingthe current video block using at least a block vector pointing to avideo frame containing the current video block, and wherein the palettemode includes encoding the current video block using a palette ofrepresentative sample values.

52. The method of clause 51, wherein the format rule further specifiesthat the coded representation does not include a pred_mode_flag, apred_mode_ibc_flag, and/or a pre_mode_plt_flag, in case that themodeType is the MODE_TYPE_IBC or the MODE_TYPE_PALETTE.

53. The method of clause 51, wherein the coded representation includesan index indicating a mode type used for the conversion instead of amode_constraint_flag.

54. The method of any of clauses 1 to 53, wherein the conversionincludes encoding the video into the coded representation.

55. The method of any of clauses 1 to 53, wherein the conversionincludes decoding the coded representation to generate the video.

56. A video processing apparatus comprising a processor configured toimplement a method recited in any one or more of clauses 1 to 55.

57. A computer readable medium storing program code that, when executed,causes a processor to implement a method recited in any one or more ofclauses 1 to 55.

58. A computer readable medium that stores a coded representation or abitstream representation generated according to any of the abovedescribed methods.

The third set of clauses describe certain features and aspects of thedisclosed techniques in the previous section (e.g., items 25-33).

1. A method of video processing, comprising: determining, for aconversion between a current video block of a video and a codedrepresentation of the video, whether a certain partitioning scheme isallowed for the current video block according to a rule that depends ona coding mode type used for representing the current video block in thecoded representation and a dimension of the current video block; andperforming the conversion based on the determining.

2. The method of clause 1, wherein the certain partitioning schemecomprises a QT (quaternary tree) split in which the current video blockis split into four parts in both horizontal and vertical directions, avertical TT (ternary tree) split in which the current video block issplit into three parts in a vertical direction, a horizontal TT split inwhich the current video block is split into three parts in a horizontaldirection, a vertical BT (binary tree) split in which the current videoblock is split into two parts in a vertical direction, and/or ahorizontal BT split in which the current video block is split into twoparts in a horizontal direction.

3. The method of clause 1, wherein the rule specifies that a QT(quaternary tree) split is disallowed for the current video block incase 1) that the coded representation includes a MODE_TYPE_INTER valuecorresponding to the coding mode type in which an inter mode only isallowed for the current video block and 2) that both of a width and aheight of the current video block are 8.

4. The method of clause 1, wherein the rule specifies that a TT (ternarytree) split is disallowed for the current video block in case 1) thatthe coded representation includes a MODE_TYPE_INTER value correspondingto the coding mode type in which an inter mode only is allowed for thecurrent video block and 2) that a multiplication of a width and a heightof the current video block is 64.

5. The method of clause 4, wherein the rule further specifies that avertical TT (ternary tree) split is disallowed in a case that the codedrepresentation includes a MODE_TYPE_INTER value and the width and theheight of the current video block are 16 and 4, respectively.

6. The method of clause 4, wherein the rule further specifies that ahorizontal TT (ternary tree) split is disallowed in a case that thecoded representation includes a MODE_TYPE_INTER value and the width andthe height of the current video block are 4 and 16, respectively.

7. The method of clause 1, wherein the rule specifies that a BT (binarytree) split is disallowed for the current video block in case 1) thatthe coded representation includes a MODE_TYPE_INTER value correspondingto the coding mode type in which an inter mode only is allowed for thecurrent video block and 2) that a multiplication of a width and a heightof the current video block is 32.

8. The method of clause 7, wherein the rule further specifies that avertical BT (binary tree) split is disallowed in a case that the codedrepresentation includes a MODE_TYPE_INTER value and the width and theheight of the current video block are 8 and 4, respectively.

9. The method of clause 7, wherein the rule specifies that a horizontalBT (binary tree) split is disallowed in a case that the codedrepresentation includes a MODE_TYPE_INTER value and the width and theheight of the current video block are 4 and 8, respectively.

10. A method of video processing, comprising: performing a conversionbetween a video block of a video and a coded representation of thevideo, wherein the coded representation conforms to a format rule,wherein the format rule specifies that a characteristic of the videoblock controls whether a syntax element in the coded representationindicates a prediction mode of the video block.

11. The method of clause 10, wherein the characteristic of the videoblock includes at least one of color components or a dimension of thevideo block.

12. The method of clause 10 or 11, wherein the format rule furtherspecifies that the syntax element indicates the prediction mode of thevideo block corresponding to a chroma block.

13. The method of any of clauses 10 to 12, wherein the format rulefurther specifies that the syntax element does not indicate theprediction mode of the video block corresponding to a luma block and theprediction mode of the video block corresponding to the luma block isincluded in the coded representation.

14. The method of clause 13, wherein the video block has a width and aheight that are greater than 4.

15. A method of video processing, comprising: performing a conversionbetween a video region of a first component of a video and a codedrepresentation of the video, wherein the coded representation conformsto a format rule, wherein the format rule specifies whether and/or how asyntax field is configured in the coded representation to indicate adifferential quantization parameter for the video region depends on asplitting scheme used for splitting samples of the first component.

16. The method of clause 15, wherein the format rule further specifieswhether and/or how the syntax field is configured in the codedrepresentation is independent of a splitting scheme used for splittingsamples of a second component of the video.

17. The method of clause 15 or 16, wherein the first component is a lumacomponent and the second component is a chroma component.

18. The method of clause 15 or 16, wherein the first component is achroma component and the second component is a luma component.

19. The method of clause 15, wherein the format rule further specifiesto include information related to the differential quantizationparameter at most once in a specific region in which a luma componentand a chroma component share a same mode type.

20. The method of clause 19, wherein the specific region corresponds toa quantization group.

21. A method of video processing, comprising: performing a conversionbetween a video region of a first component of a video and a codedrepresentation of the video according to a rule, wherein the rulespecifies, in case that a dual tree and/or a local dual tree codingstructure is applied to the video region, that a variable related to adifferential quantization parameter of the first component is notmodified during a decoding or parsing process of a second component ofthe video.

22. The method of clause 21, wherein the local dual tree structure isapplied to the video region in case that a restriction on a smallestallowed size for a chroma block is applied to the video region.

23. The method of clause 21 or 22, wherein the first component is a lumacomponent and the second component is a chroma component.

24. The method of clause 21 or 22, wherein the first component is achroma component and the second component is a luma component.

25. The method of any of clauses 21 to 24, wherein the differentialquantization parameter indicates a difference in a quantization valueapplied to the video block and a previous quantization value applied toa neighboring video block.

26. The method of any of clauses 1 to 25, wherein the performing of theconversion includes generating the coded representation from the video.

27. The method of any of clauses 1 to 25, wherein the performing of theconversion includes generating the video from the coded representation.

28. A video processing apparatus comprising a processor configured toimplement a method recited in any one or more of clauses 1 to 27.

29. A computer readable medium storing program code that, when executed,causes a processor to implement a method recited in any one or more ofclauses 1 to 27.

30. A computer readable medium that stores a coded representation or abitstream representation generated according to any of the abovedescribed methods.

The disclosed and other solutions, examples, embodiments, modules andthe functional operations described in this document can be implementedin digital electronic circuitry, or in computer software, firmware, orhardware, including the structures disclosed in this document and theirstructural equivalents, or in combinations of one or more of them. Thedisclosed and other embodiments can be implemented as one or morecomputer program products, i.e., one or more modules of computer programinstructions encoded on a computer readable medium for execution by, orto control the operation of, data processing apparatus. The computerreadable medium can be a machine-readable storage device, amachine-readable storage substrate, a memory device, a composition ofmatter effecting a machine-readable propagated signal, or a combinationof one or more them. The term “data processing apparatus” encompassesall apparatus, devices, and machines for processing data, including byway of example a programmable processor, a computer, or multipleprocessors or computers. The apparatus can include, in addition tohardware, code that creates an execution environment for the computerprogram in question, e.g., code that constitutes processor firmware, aprotocol stack, a database management system, an operating system, or acombination of one or more of them. A propagated signal is anartificially generated signal, e.g., a machine-generated electrical,optical, or electromagnetic signal, that is generated to encodeinformation for transmission to suitable receiver apparatus.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand-alone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

The processes and logic flows described in this document can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random-access memory or both. The essential elements of a computer area processor for performing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto optical disks, or optical disks. However, a computerneed not have such devices. Computer readable media suitable for storingcomputer program instructions and data include all forms of non-volatilememory, media and memory devices, including by way of examplesemiconductor memory devices, e.g., EPROM, EEPROM, and flash memorydevices; magnetic disks, e.g., internal hard disks or removable disks;magneto optical disks; and CD ROM and DVD-ROM disks. The processor andthe memory can be supplemented by, or incorporated in, special purposelogic circuitry.

While this patent document contains many specifics, these should not beconstrued as limitations on the scope of any subject matter or of whatmay be claimed, but rather as descriptions of features that may bespecific to particular embodiments of particular techniques. Certainfeatures that are described in this patent document in the context ofseparate embodiments can also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment can also be implemented in multipleembodiments separately or in any suitable sub combination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Moreover, the separation of various system components in theembodiments described in this patent document should not be understoodas requiring such separation in all embodiments.

Only a few implementations and examples are described and otherimplementations, enhancements and variations can be made based on whatis described and illustrated in this patent document.

1. A method of processing video data, comprising: determining, for aconversion between a current video block of a video and a bitstream ofthe video, whether a partitioning scheme is allowed for the currentvideo block according to a rule that depends on a mode type of thecurrent video block and a dimension of the current video block; andperforming the conversion based on the determining.
 2. The method ofclaim 1, wherein the partitioning scheme comprises: a QT (quaternarytree) split in which the current video block is split into four parts inboth horizontal and vertical directions, a vertical TT (ternary tree)split in which the current video block is split into three parts in avertical direction, a horizontal TT split in which the current videoblock is split into three parts in a horizontal direction, a vertical BT(binary tree) split in which the current video block is split into twoparts in a vertical direction, or a horizontal BT split in which thecurrent video block is split into two parts in a horizontal direction.3. The method of claim 1, wherein the dimension of the current videoblock comprises a height or a width of the current video block.
 4. Themethod of claim 1, wherein the rule specifies that a QT split isdisallowed for the current video block in case 1) that the mode type ofthe current video block is MODE_TYPE_INTER in which inter coding modesonly are allowed for the current video block and 2) that both of a widthand a height of the current video block are
 8. 5. The method of claim 1,wherein the rule specifies that a TT (ternary tree) split is disallowedfor the current video block in case 1) that the mode type of the currentvideo block is MODE_TYPE_INTER in which inter coding modes only areallowed for the current video block and 2) that a multiplication of awidth and a height of the current video block is
 64. 6. The method ofclaim 5, wherein the rule specifies that a vertical TT split isdisallowed for the current video block when the width of the currentvideo block is equal to 16, and the height of the current video block isequal to
 4. 7. The method of claim 5, wherein the rule specifies that ahorizontal TT split is disallowed for the current video block when thewidth of the current video block is equal to 4, and the height of thecurrent video block is equal to
 16. 8. The method of claim 1, whereinthe rule specifies that a BT (binary tree) split is disallowed for thecurrent video block in case 1) that the mode type of the current videoblock is MODE_TYPE_INTER in which inter coding modes only are allowedfor the current video block and 2) that a multiplication of a width anda height of the current video block is
 32. 9. The method of claim 8,wherein the rule specifies that a vertical BT split is disallowed forthe current video block when the width of the current video block isequal to 8, and the height of the current video block is equal to
 4. 10.The method of claim 8, wherein the rule specifies that a horizontal BTsplit is disallowed for the current video block when the width of thecurrent video block is equal to 4, and the height of the current videoblock is equal to
 8. 11. The method of claim 1, wherein the conversioncomprises encoding the current video block into the bitstream.
 12. Themethod of claim 1, wherein the conversion comprises decoding the currentvideo block from the bitstream.
 13. An apparatus for processing videodata comprising a processor and a non-transitory memory withinstructions thereon, wherein the instructions upon execution by theprocessor, cause the processor to: determine, fora conversion between acurrent video block of a video and a bitstream of the video, whether apartitioning scheme is allowed for the current video block according toa rule that depends on a mode type of the current video block and adimension of the current video block; and perform the conversion basedon the determining.
 14. The apparatus of claim 13, wherein the rulespecifies that a QT split is disallowed for the current video block incase 1) that the mode type of the current video block is MODE_TYPE_INTERin which inter coding modes only are allowed for the current video blockand 2) that both of a width and a height of the current video block are8.
 15. The apparatus of claim 13, wherein the rule specifies that a TT(ternary tree) split is disallowed for the current video block incase 1) that the mode type of the current video block is MODE_TYPE_INTERin which inter coding modes only are allowed for the current video blockand 2) that a multiplication of a width and a height of the currentvideo block is
 64. 16. The apparatus of claim 13, wherein the rulespecifies that a BT (binary tree) split is disallowed for the currentvideo block in case 1) that the mode type of the current video block isMODE_TYPE_INTER in which inter coding modes only are allowed for thecurrent video block and 2) that a multiplication of a width and a heightof the current video block is
 32. 17. A non-transitory computer-readablestorage medium storing instructions that cause a processor to:determine, fora conversion between a current video block of a video anda bitstream of the video, whether a partitioning scheme is allowed forthe current video block according to a rule that depends on a mode typeof the current video block and a dimension of the current video block;and perform the conversion based on the determining.
 18. Thenon-transitory computer-readable storage medium of claim 17, wherein therule specifies that a QT split is disallowed for the current video blockin case 1) that the mode type of the current video block isMODE_TYPE_INTER in which inter coding modes only are allowed for thecurrent video block and 2) that both of a width and a height of thecurrent video block are 8; the rule specifies that a TT (ternary tree)split is disallowed for the current video block in case 1) that the modetype of the current video block is MODE_TYPE_INTER in which inter codingmodes only are allowed for the current video block and 2) that amultiplication of a width and a height of the current video block is 64;or the rule specifies that a BT (binary tree) split is disallowed forthe current video block in case 1) that the mode type of the currentvideo block is MODE_TYPE_INTER in which inter coding modes only areallowed for the current video block and 2) that a multiplication of awidth and a height of the current video block is
 32. 19. Anon-transitory computer-readable recording medium storing a bitstream ofa video which is generated by a method performed by a video processingapparatus, wherein the method comprises: determining, for a currentvideo block of a video, whether a partitioning scheme is allowed for thecurrent video block according to a rule that depends on a mode type ofthe current video block and a dimension of the current video block; andgenerating the bitstream based on the determining.
 20. Thenon-transitory computer-readable recording medium of claim 19, whereinthe rule specifies that a QT split is disallowed for the current videoblock in case 1) that the mode type of the current video block isMODE_TYPE_INTER in which inter coding modes only are allowed for thecurrent video block and 2) that both of a width and a height of thecurrent video block are 8; the rule specifies that a TT (ternary tree)split is disallowed for the current video block in case 1) that the modetype of the current video block is MODE_TYPE_INTER in which inter codingmodes only are allowed for the current video block and 2) that amultiplication of a width and a height of the current video block is 64;or the rule specifies that a BT (binary tree) split is disallowed forthe current video block in case 1) that the mode type of the currentvideo block is MODE_TYPE_INTER in which inter coding modes only areallowed for the current video block and 2) that a multiplication of awidth and a height of the current video block is 32.